Web Sustainability Guidelines (WSG)

W3C Group Note Draft

More details about this document
This version:
https://www.w3.org/TR/2026/DNOTE-web-sustainability-guidelines-20260703/
Latest published version:
https://www.w3.org/TR/web-sustainability-guidelines/
Latest editor's draft:
https://w3c.github.io/sustainableweb-wsg/
History:
https://www.w3.org/standards/history/web-sustainability-guidelines/
Commit history
Lead Editor:
Alexander Dawson (Invited Expert)
Editor:
Rose Newell (Invited Expert)
Authors:
See acknowledgments
Feedback:
GitHub w3c/sustainableweb-wsg (pull requests, new issue, open issues)
Supplements:
Sustainable Tooling And Reporting (STAR)
WSG Resources
Web Sustainability Laws and Policies
WSG Impact Measurement
WSG Benefits
WSG at a Glance
WSG Quick Reference

Copyright © 2026 World Wide Web Consortium. W3C® liability, trademark and permissive document license rules apply.

Abstract

Web Sustainability Guidelines (WSG) provide actionable recommendations to help digital teams make informed, sustainable decisions. In considering different aspects of work and the web, these guidelines address the planet, people, and prosperity (PPP) impacts of digital products and services. They are interdisciplinary and cover artificial intelligence and emerging web technologies.

Some guidelines reference existing documents and specifications from W3C and other organizations. This approach highlights the importance of intersectionality and collaboration, rather than reinterpreting established recommendations. While WSG prioritizes web technologies, it can also support broader organizational sustainability efforts.

WSG can also serve as a practical bridge to support broader organizational sustainability initiatives and transformation, helping teams apply web-focused guidance to broader environmental, social, and governance efforts.

Organizations are encouraged to make sustainability progress over time. Setting realistic goals and tracking progress will help teams achieve lasting web sustainability. For implementation guidance, see the "additional information" sections in this document and the supporting documents.

Status of This Document

This section describes the status of this document at the time of its publication. A list of current W3C publications and the latest revision of this technical report can be found in the W3C standards and drafts index.

This document has been reviewed by members of the Sustainable Web Interest Group and other interested parties. This Interest Group published the WSG draft to raise awareness of the guidelines and to encourage discussion and adoption. Publication of these guidelines does not imply that they will affect the work undertaken by other W3C groups; the Interest Group will monitor related work as appropriate.

Feedback is welcome and should be submitted via GitHub. A free GitHub account is required to file issues. Past discussions are archived on the public-sustainableweb@w3.org (archive) mailing list.

No preliminary interoperability or implementation reports exist at this time. However, the Interest Group is exploring models for web sustainability to inform tooling, large-scale studies, and future WSG guidance.

This document was published by the Sustainable Web Interest Group as a Group Note Draft using the Note track.

Group Note Drafts are not endorsed by W3C nor its Members.

This is a draft document and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to cite this document as other than a work in progress.

The W3C Patent Policy does not carry any licensing requirements or commitments on this document.

This document is governed by the 18 August 2025 W3C Process Document.

1. Introduction

Plain language summary of the Introduction:

1.1 Background on WSG

1.1.1 Web sustainability overview

WSG defines web sustainability as follows:

An approach to designing, developing, and operating digital products and services that leads to a web that is as clean, efficient, open, honest, regenerative and resilient as possible. [MANIFESTO]

Web sustainability goes beyond reducing harm: it is also about restoring ecosystems and supporting communities to thrive. The web can be both part of the problem and a catalyst for solutions.

WSG aims to foster a more ethical, humane, and inclusive web. The guidelines emphasize systems thinking, intersectionality, and cross-functional collaboration as essential to sustainable development.

WSG understands the key terms from its definition as follows:

  • Clean: hosted using low-carbon or renewable energy;
  • Efficient: using the fewest resources possible;
  • Open: transparent, accessible, and user-controlled;
  • Honest: avoiding manipulation, exploitation, or deceptive patterns;
  • Regenerative: supporting communities and ecosystems;
  • Resilient: designed to endure and adapt under changing circumstances.

This builds on the existing pillars of web sustainability:

  • Planet: Protecting and promoting healthy ecosystems.
  • People: Safeguarding individuals, communities, and society as a whole.
  • Prosperity: Following practices grounded in good governance, resilience and shared equity.

Web Sustainability Guidelines (WSG) explore how to make web products and services more sustainable for the planet, people, and prosperity. Web sustainability is about more than strictly environmental concerns, as factors such as accessibility, internationalization, privacy, and security will influence the long-term viability of a project. These principles should always be observed without compromise in the pursuit of web sustainability.

Note
WSG was originally developed by the Sustainable Web Design Community Group. From April 2022, over 100 experts contributed to the first draft, which was refined through GitHub and regular meetings. In October 2024, the group and its work became part of W3C.

1.1.2 The importance of web sustainability

  • Internet-related emissions now surpass those of the aviation industry, making web sustainability a critical lever for climate action. [ICT-IMPACT] [COMMS] [SHIFT]
  • Seven of nine planetary boundaries have been crossed, with Internet-related technologies accelerating these overshoots. WSG provides a framework to reverse this trend through measurable, evidence-based practices.
  • The integration of emerging technologies such as artificial intelligence can significantly increase digital resource consumption, highlighting the need to consider sustainability when developing and deploying new web capabilities.
  • Digital impact scales with size: Larger websites and online resources have greater sustainability challenges, but also more opportunities to implement changes. Unlike other infrastructure, the web lends itself to agile and iterative improvement.

1.1.3 Sustainability considerations

Web sustainability requires systems thinking and cross-functional collaboration. Digital services operate within complex environmental, social, and economic systems, meaning decisions made in one area may influence outcomes in others. Consideration of interdependencies can help to avoid unintended consequences and identify opportunities.

While these guidelines promote web sustainability across multiple areas, they do not cover all possible environmental improvements, methods or strategies. Web sustainability is an evolving field, and gaps in research or established best practices may exist. Always explore additional approaches that may better suit the context.

WSG focuses on web technologies, but just like the web is connected to almost everything we do, WSG also examines less obvious details that impact web sustainability, even if their relationship to digital services and the web may seem tenuous at first glance. Organizations should consider these broader impacts when setting targets, reporting, and ensuring compliance with regulations.

1.2 WSG layers of guidance

WSG is designed for a diverse audience, including developers, designers, policymakers, and more. It provides multiple layers of guidance to address different needs.

Together, these layers provide a structured approach similar to other W3C guidelines and help implementers create more sustainable projects. Guidelines describe web sustainability goals, success criteria define measurable expectations, and additional information provides context and examples to support implementation.

Web Sustainability Guidelines (WSG) are organized into four categories, reflecting different roles involved in digital services and the web. Readers should review all sections, even those not nominally related to their assumed responsibilities. This is important, as some Success Criteria have relevance outside their assigned category. While WSG is comprehensive, additional web sustainability improvements exist outside the scope of these guidelines.

Note

This interactive specification lets you filter success criteria by interest; standards listed in relationships are available as filters and are cross-referenced in the resources document.

1.3 Testing and metrics

WSG is designed to be testable through automated tools and human evaluation. It applies to a wide range of web technologies and was developed with input from global experts.

WSG emphasizes data-driven decision-making. Success criteria are backed by evidence and best practices, with supporting materials available in the resources document.

1.3.1 Challenges in measurement

  • Data gaps exist across the Internet stack. For example, energy use data for servers, networks, and devices is often incomplete.
  • Systemic interdependencies create butterfly effects, whereby actions in one area may impact others. For example, deploying energy-efficient hardware may reduce energy consumption and have the side-benefit of local noise reduction, but that hardware must be manufactured, and that in turn necessitates the mining of rare earth metals.
  • Carbon tunnel vision leads to prioritization of energy emissions over material waste, e-waste, and water use, or the planet over the people and prosperity aspects of PPP.
  • Environmental impact is rarely all or nothing. Implementers should do what they can and mitigate remaining negative impacts to improve their overall impact.

Environmental impacts associated with digital services extend beyond energy consumption and greenhouse gas (GHG) emissions. Material use, electronic waste, water consumption, and chemical pollution associated with digital infrastructure should also be considered wherever the data and methodologies are available [VARIABLES].

Web sustainability improvements can involve trade-offs. For example, actions that reduce water use may increase energy demand, while performance optimizations may influence accessibility or device compatibility. Implementers should evaluate potential trade-offs carefully to ensure improvements in one area do not unintentionally cause harm in another.

1.3.2 Impact

The Web Sustainability Guidelines (WSG) Impact Measurement resource defines a framework for assessing the impact of WSG guidelines across three categories: people, planet, and prosperity. Each guideline is assigned an impact rating (indeterminate, low, medium, or high) and a timeframe (short, medium, or long) indicating when the impact is expected to be observed.

These inputs are used to calculate an impact score for each guideline. The score helps organisations compare guidelines and prioritise actions based on relative impact and timeframe. Higher scores indicate higher impact achieved over a shorter timeframe. The resulting scores are included in the resource.

Where quantitative measurement is not possible, ratings are based on available research and expert input. Each guideline includes a rationale for its ratings and timeframe, and where appropriate, suggested metrics to support evaluation.

1.3.3 Call to action

Web Sustainability Guidelines relies on multiple implementors:

  • Authors (e.g., designers, developers, writers, decision-makers).
  • User agents (e.g., browsers).
  • Authoring tools.

Examples of their impact include rendering performance and accurate measurement of energy use through developer tooling. Authoring tools also support web sustainability by producing efficient code, reducing waste, and delivering results in the most sustainable way possible.

Note

Tools or user agents that provide WSG insights must avoid fingerprinting risks. For example, tracking users via unique identifiers, scores, or patterns. Energy metrics should be aggregated to avoid identifying individual users.

Beyond this, web sustainability requires champions across all roles:

  • Individuals: Advocate for web sustainability, educate peers, and start small.
  • Designers/Developers: Prioritize accessibility, security, privacy, internationalization, performance, and low-carbon infrastructure.
  • Browsers/Hardware Vendors: Optimize efficiency, adopt circular economy practices, and ensure operations and supply chains avoid exploitative, unsustainable, or unsafe practices.
  • Regulators: Embed digital sustainability into climate policies and reduction targets.

Sustainability is a shared responsibility. Different champions may lead, support, or advocate for different guidelines depending on their expertise and context.

As research, technologies, and web sustainability practices evolve, WSG will continue to be updated. Contribute via GitHub to help ensure the guidance reflects current knowledge and practical implementation experience.

1.4 Conformance

This section defines requirements for conformance to WSG, including optional conformance claims and guidance to avoid greenwashing.

1.4.1 Requirements

Conformance to WSG, either partially or in full, means a specific set of WSG criteria is fulfilled. Conformance with WSG can be established for success criteria, guidelines, sections (role-based), or the entire specification.

Partial conformance on the success criterion level

A digital product or service conforms to a specific success criterion when it meets the requirements in that success criterion.

Partial conformance on the guideline level

A digital product or service conforms to an individual guideline when it meets all of the success criteria in that guideline. If a success criterion cannot be applied, it does not affect conformance of that guideline.

Note

A success criterion may not be applicable, for example, it may relate to video content and the product or service being evaluated does not include video.

Partial conformance on the section level

Section-level (role-based) conformance can be achieved by conforming to all guidelines within one section. For example, if all guidelines in the Web Development section are met, the website or organization is considered partially conformant for that section.

These are called:

  • Partially conformant: UX
  • Partially conformant: Web Development
  • Partially conformant: Hosting and Infrastructure
  • Partially conformant: Business and Product
Full conformance

A digital product or service fully conforms to WSG when it meets all success criteria across all guidelines.

Note

Full conformance may not be achievable for all products or services. Pragmatism and progress over perfection should be considered paramount when implementing and following these guidelines.

1.4.2 Claims

Conformance claims are optional. If made, they must include:

  1. Date of the claim.
  2. Guidelines title and URI: "Web Sustainability Guidelines at https://www.w3.org/TR/web-sustainability-guidelines/".
  3. Conformance details: A list of the success criteria, guidelines and/or sections in WSG that are met.

Implementers can conform to WSG without making a claim.

In addition to the conformance claim itself, it can be helpful to include:

  • A statement of intent of which standards and regulations you commit to complying with.
  • Additional information is provided to assist users, including steps taken beyond this specification to improve web sustainability and metrics showing the impact of changes, with dates or time periods for any supporting data clearly stated.
Note

Recording claims and supporting evidence in a sustainability statement can help demonstrate compliance with reduction targets, internal scope accounting, or regulations.

Using these guidelines can help organizations to better align with existing and emerging laws, policies, and reporting schemes related to environmental and sustainability practices. They do not guarantee full compliance and should be applied alongside applicable legal and regulatory requirements.

1.4.3 Greenwashing

Greenwashing is misleading the public to believe that a company or other entity is doing more to protect the environment than it is. False claims are acknowledged to potentially harm users in other fields. In sustainability, harm arising from this threat vector can impact not only users of a product or service, but also to the wider ecosystem and society.

To avoid this:

  • Do not claim WSG conformance as evidence of achieving total sustainability, as there will always be gaps in this document's coverage.
  • Avoid presenting partial improvements as evidence of achieving sustainability.
  • Communicate sustainability efforts transparently, only making verifiable claims alongside supporting evidence.

1.5 Relationships

Note

The guidelines and standards that WSG is based on are always changing. Some, called "living" or "evergreen" standards, update often and could quickly affect how relevant this document is. Others update less often, so changes might not impact WSG until a new version comes out.

Because of this, anyone using WSG should regularly check for updates to best practices based on new research or data. They should also make sure their tools are up to date to stay compliant with the latest guidance.

1.5.1 W3C specifications

Relationship to Ethical Principles for Web Machine Learning [webmachinelearning-ethics]
This W3C document addresses ethical considerations for using machine learning on the web. WSG integrates these principles to ensure AI addresses sustainable and responsible digital practices.
Relationship to Ethical Web Principles [ethical-web-principles]
This W3C document outlines ethical principles for the web, including Principle 2.9, which states "The web is an environmentally sustainable platform." WSG aligns with this principle to promote sustainability in digital practices.
Relationship to Mitigating Browser Fingerprinting [fingerprinting-guidance]
This W3C document defines types of browser fingerprinting and ways to mitigate privacy risks. WSG ensures web sustainability efforts respect user privacy and data protection in line with these guidelines.
Relationship to Privacy Principles [privacy-principles]
This W3C document provides privacy principles to guide the development of the web as a trustworthy platform. WSG connects privacy, security, and web sustainability to create responsible digital practices.
Relationship to Web Content Accessibility Guidelines (WCAG)
[WCAG] provides recommendations for making web content more accessible. WSG aligns with WCAG to ensure digital experiences are both accessible and sustainable. Conflicts between WCAG and WSG are unlikely by nature, but where apparent, should be assessed according to the conformance note.
Relationship to Web Platform Design Principles [design-principles]
This W3C document contains design principles for web platform technologies. WSG incorporates these principles to advance sustainable best practices.

1.5.2 Other standards

Relationship to Global Reporting Initiative (GRI)
[GRI] provides the world's most widely used standards for web sustainability reporting. WSG provides GRI-aligned metrics to support transparency and compliance in sustainability reporting, with data evolving as measurability improves.

1.5.3 Best practices

Relationship to AFNOR (Association Française de Normalisation)
AFNOR SPEC 2201 provides guidelines for web sustainability in digital practices. WSG references this document to align with recognized sustainability frameworks.
Relationship to ARCEP (Autorité de Régulation des Communications Électroniques, des Postes et de la Distribution de la Presse)
The General Policy Framework for the Ecodesign of Digital Services provides guidelines for sustainable digital service design. WSG aligns with this framework to assist with compliance and sustainability in digital practices.
Relationship to Amazon Web Services (AWS) and Microsoft Azure Well-Architected Frameworks
The AWS and Azure Well-Architected Frameworks provide best practices for optimizing digital resources. WSG cross-references these frameworks where web sustainability goals overlap with resource efficiency and responsible cloud usage.
Relationship to Center for Democracy & Technology (CDT)
Human Rights and Technical Standard-Setting for the Web [HR-Spec] emphasizes the importance of human rights in web standards, including accessibility, privacy, internationalization, and security. WSG integrates these principles to ensure digital practices are both sustainable and ethically responsible.
Relationship to GR491 (Handbook of Sustainable Digital Design)
Published by the Institute for Sustainable IT, GR491 is a handbook of best practices for sustainable digital services. WSG cross-references this handbook to incorporate proven web sustainability strategies.
Relationship to GreenIT
An open-source initiative providing guidelines to reduce the digital carbon footprint. WSG adopts GreenIT's best practice guidelines for web eco-design recommendations to promote sustainable IT practices.
Relationship to OpQuast
A quality assurance provider offering checklists for digital quality through its Digital Quality Framework WSG aligns with OpQuast's guidelines to enhance performance and resource efficiency for web sustainability.
Relationship to United Nations (UN) Sustainable Development Goals (SDGs)
The UN's SDGs are global targets for sustainable change. WSG maps digital practices to relevant SDG targets to contribute to broader sustainability efforts.
Note

When WSG guidance conflicts with those in other documents, first check whether an alternative solution can meet both web sustainability and compliance obligations. If a conflict remains, assess risks: following the recommendation with lower sustainability risks unless WSG is overridden by higher authority, such as legislation.

1.6 WSG supporting documents

WSG specification provides a stable, referenceable foundation. Supporting documents expand on it with implementation guidance, methodologies, and strategies for working with new technologies. Supporting documents include:

For more, see the W3C Sustainable Web Interest Group GitHub for educational resources related to WSG; other resources, such as tooling, may be referenced as needed.

2. User Experience Design

If you are creating content and systems designed for users, then whether you know it or not, you are working in user experience (UX).

User experience design contributes to sustainability by keeping projects usable, efficient, and trusted over time, reducing unnecessary repetition and resource use. When difficult to use, they often require more support, more retries, and may be abandoned or replaced earlier than necessary. This shortens lifespans and increases demand for redesign and redevelopment—effects that accumulate across users and over time..

Goals include:

Benefits include:

Plain language summary of the User Experience Design:

2.1 Identify, assess, disclose, review, and mitigate sustainability impacts

Assess and report the planet, people, and prosperity impacts of digital projects, and plan measurable reductions to the real-world effects of their activity.

Success Criterion: Impact analysis

Resources

Review the planet, people, and prosperity impacts of your project at the start and at regular intervals. Record the main issues you identify, where improvements are needed, and the progress you make. Reflect these findings in your public-facing governance documents and project reporting.

Success Criterion: External impact

Resources

Create a plan to reduce the non-digital environmental and social impacts of digital activities associated with your project. Include impacts from logistics and delivery emissions, infrastructure emissions, local health effects, and supply chain pressures. Use measurable actions to improve external planet, people, and prosperity outcomes.

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Tags

Accessibility, Compatibility, Hardware, Ideation, Networking, Performance, Privacy, Reporting, Research, Social Equity, Software

2.2 Understand user requirements or constraints

Identify and involve users and affected communities, and research their needs.

Success Criterion: Audience evaluation

Resources

Identify the primary and secondary users, and affected communities, for the project. Use research, testing, analytics, and reviews to understand their needs and the project's impact on them. Involve users throughout the project.

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Accessibility, Compatibility, Ideation, Patterns, Reporting, KPIs, Privacy, Research, Social Equity, UI, Usability

2.3 Integrate sustainability into every stage of the ideation process

Design and review sustainable branding and experiences, involve users throughout the process, and reduce unnecessary development and environmental impact through early testing and environmentally aware design.

Success Criterion: Sustainable brand development

Resources

Optimize approved branding materials and assets to meet the organization’s sustainability requirements before release and review them regularly after launch. Where brand guidelines exist, include information about the environmental impact of materials and assets, along with guidance for sustainable production, use, and disposal.

Success Criterion: Wireframes and prototypes

Resources

Use wireframes and rapid prototypes to test ideas early, build agreement quickly, reduce risk, and avoid unnecessary development work and resource use.

Success Criterion: Participation and testing

Resources

Use participatory design methods throughout the design process. Involve users in testing and iteration, and give communities opportunities to share their knowledge and experience to improve the product or service.

Success Criterion: Environmental ideation

Resources

Address planetary needs and environmental boundaries during the ideation phase. This can include creating non-user, non-human personas, such as animal- or planet-focused perspectives, and developing climate-specific user stories and sprints.

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Accessibility, Ideation, KPIs, Research, Social Equity, Software, Strategy, UI

2.4 Design efficient and streamlined user journeys

Design clear, efficient journeys that help users complete tasks and find content with minimal effort.

Success Criterion: Efficient paths

Resources

Make tasks simple and efficient to complete. Help users understand what is required at the start of a task, reduce unnecessary choices, and show how long journeys are expected to take.

Success Criterion: Patterns for efficiency

Resources

Design user journeys that are clear and efficient. Use established design patterns that people already understand.

Success Criterion: Content discovery

Resources

Provide a human-readable sitemap, especially for large, complex, or legacy websites where navigation is not straightforward. Keep it regularly updated. Provide clear and accessible navigation and search features so users can quickly find the content or services they need. Use lightweight and efficient ways to help users discover new content and services, including news pages, updates, and changelogs.

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Accessibility, Content, HTML, Marketing, Patterns, Performance, Privacy, Social Equity, UI, Usability

2.5 Design to assist and not to distract

Give users control over notifications and focus, prioritize task-relevant content, and avoid designs that distract or unnecessarily extend engagement.

Success Criterion: Respect user attention

Resources

Ensure users can control when and how they receive information, while respecting their attention, focus, and mental effort.

Success Criterion: Distraction-free design

Resources

Show users information relevant to their current task and avoid unnecessary interruption and competing interface elements. Delay or collapse information not immediately needed, but keep it easy to find. Only show pop-ups, modal windows, or other disruptive interface elements when the user chooses to open them. Use decorative design only when it improves the user experience, and make optional assets removable or turned off by default. Do not remove information or functionality that may be important for accessibility, safety, or different user needs.

Success Criterion: Remove engagement traps

Resources

Avoid design patterns that engage users longer than necessary, such as infinite scroll or disabling standard browser controls and navigation features.

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Accessibility, Assets, Content, Patterns, Performance, Privacy, Social Equity, UI, Usability

2.6 Avoid being manipulative or deceptive

Avoid deceptive patterns, clearly label ads, respect consent for tracking, and ensure search, sharing, and discoverability practices prioritize user needs over optimization or manipulation.

Success Criterion: Deceptive design patterns

Resources

Avoid deceptive design patterns that pressure or mislead users. This includes practices such as bait and switch, hidden fees, or fake scarcity.

Success Criterion: Advertisements

Resources

Clearly label advertisements and sponsored content. Deliver advertising in a lightweight and minimally disruptive way while enabling users to control the experience.

Success Criterion: Analytics and tracking

Resources

Remove unnecessary analytics and tracking, and respect user consent over tracking analytics.

Success Criterion: Search Engine Optimization

Resources

Optimize content for search and social sharing in ways that support user needs rather than manipulation. Do not misuse accessibility features, create low-quality content, or add unnecessary duplication only to influence search rankings.

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Accessibility, Assets, Compatibility, JavaScript, JavaScript, Patterns, Privacy, Security, Social Equity, UI, Usability

2.7 Make deliverables understandable and reusable

Create discoverable, maintainable, and reusable documentation and code resources that support long-term understanding, reuse, and sustainability.

Success Criterion: Deliverables reusability

Resources

Create documentation and other deliverables in reusable formats to reduce duplicated work and support long-term sustainability.

Success Criterion: Deliverables documentation

Resources

Document functionality and technical requirements in clear and easy-to-maintain resources. Keep documentation updated over time and provide guidance for replacing or retiring outdated information.

Success Criterion: Deliverables readability

Resources

Provide developers with access to source code and code comments so they can easily understand, maintain, and reuse the code.

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Accessibility, Assets, Content, Education, Patterns, Software

2.8 Use a design system for interface consistency

Use design systems and established patterns to ensure consistent, efficient, and sustainable interfaces through reusable components and clear maintenance practices.

Success Criterion: Design system

Resources

Use a design system for large projects or projects with many contributors to improve consistency, performance, and long-term sustainability. Use reusable components based on web standards, load only the components needed for each page or feature, and maintain the system through clear ownership, versioning, and updated documentation. Follow established design patterns and conventions.

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Accessibility, Assets, CSS, Education, Patterns, Strategy, UI, Usability

2.9 Optimize media to reduce resource use

Include media only when it supports user needs. Manage, optimize, and load media efficiently. Ensure users have control over playback and data use.

Success Criterion: Need for media

Resources

Only include media when it supports user experience or improves understanding and keep the number of media items to a minimum.

Success Criterion: Optimized media

Resources

Resize, optimize, and compress media for different screen sizes, devices, and user needs. Use widely supported, efficient formats that enable native playback where possible. Avoid unnecessary custom or non-native media players. Use hardware-accelerated playback when available and compatible with security requirements.

Success Criterion: Lazy loading

Resources

Incorporate lazy and/or deferred loading from the start by identifying which media elements are required immediately and which should load only on user interaction. Load large or data-intensive media only when needed, using a non-functional static facade or placeholder to defer loading until user request or interaction.

Success Criterion: User-controlled media

Resources

Disable autoplay for audio, video, and other media by default. Ensure users can control playback and resolution. Inform users about media length, format, and expected data use. Provide the option to disable data-intensive media or offer lower-bandwidth alternatives.

Success Criterion: Media management and use

Resources

Create a media management and usage policy. Include guidance on compression, rendering performance, file formats, data retention, storage, review, and deletion.

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Example

<picture> 
	<source type="image/avif" srcset="image.avif">
	<source type="image/webp" srcset="image.webp">
	<img width="100px" height="100px" src="image.jpg" alt="" loading="lazy"/>
</picture>

Tags

Accessibility, Assets, Content, HTML, Performance, Software, UI, Usability

2.10 Ensure animation is proportionate and easy to control

Use animation sparingly and efficiently, only when it supports understanding, while limiting performance impact and giving users control over motion.

Success Criterion: Need for animation

Resources

Use animation only when it supports the user experience or helps users understand content or actions.

Success Criterion: Avoiding overburdening

Resources

Limit the number and frequency of animations to reduce distraction, lower resource use, and avoid affecting device performance. Set a maximum number of replays or iterations.

Success Criterion: Control animation

Resources

Let users start, pause, stop, or control animated and moving content.

Success Criterion: Efficient animation

Resources

Keep interactive and animated content as lightweight as possible. Reduce rendering cost by accounting for formats, lengths, complexity, dimensions, quality, tooling, and implementation approach. Where multiple approaches are available, choose browser- or platform-native animation capabilities and minimize main-thread or layout-intensive work.

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Example

@media (prefers-reduced-motion: reduce) {
	body *,
	body *::before,
	body *::after {
		animation-delay: -1ms !important;
		animation-duration: 1ms !important;
		animation-iteration-count: 1 !important;
		background-attachment: initial !important;
		transition-duration: 1ms !important;
		transition-delay: -1ms !important;
		scroll-behavior: auto !important;
	}
}

Tags

Accessibility, CSS, JavaScript, Performance, UI, Usability

2.11 Use optimized web typography

Use font strategies that minimize downloads and complexity while supporting required languages and dynamic content.

Success Criterion: Pre-installed typefaces

Resources

Use system fonts or other pre-installed fonts to reduce font downloads and improve performance.

Success Criterion: Web font optimization

Resources

Limit the number and complexity of downloaded fonts. When using variable fonts, restrict supported axes and ranges to only those required by the project to reduce file size. Use the most performant font formats available and provide suitable fallback fonts to maintain readability and performance during font loading or when custom fonts cannot be loaded.

Success Criterion: Web font subsetting

Resources

Remove unused font styles, weights, and character sets. Subset fonts based on explicitly supported languages, scripts, and Unicode ranges required by the project. Where you have full control over all input and output, subset fonts to include only the relevant Unicode ranges or character sets. In cases involving dynamic content or user-generated input, provide broader script coverage and use Incremental Font Transfer (IFT) to load required font segments on demand.

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Example

font-family: -apple-system, BlinkMacSystemFont, avenir next, avenir, segoe ui, helvetica neue, helvetica, Cantarell, Ubuntu, roboto, noto, arial, sans-serif;

Tags

Accessibility, CSS, Performance, UI, Usability

2.12 Avoid unwanted notifications

Send only user-requested notifications and provide clear, accessible controls for managing preferences, opt-in, and account and contact settings.

Success Criterion: Need for notification

Resources

Only send notifications that match user preferences or that the user has explicitly requested. Avoid unnecessary emails, (SMS) messages, and push notifications. Give users clear control over each notification type.

Success Criterion: Notification settings

Resources

Let users manage their notification and messaging settings easily. Make unsubscribe, logout, and account closure options visible and accessible. Turn off optional notifications by default and enable them only after user opt-in.

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JavaScript, Privacy, UI, Usability

2.13 Reduce the impact of downloadable and physical documents

Reduce paper use through digital-first workflows, optimize and reuse accessible downloadable documents, and provide clear, user-controlled document previews and formats.

Success Criterion: Printed documents

Resources

Design workflows to reduce the need for paper documents. When paper use is necessary, reduce paper use through efficient print layouts and minimal page counts. Include print style sheets and test them with real content. Encourage the use of digital formats instead of paper storage and archiving.

Success Criterion: Optimized documents

Resources

Optimize and compress downloadable documents, provide them in accessible formats that suit different user needs, and choose open, widely supported formats (such as HTML) over proprietary file formats.

Success Criterion: Optimized delivery

Resources

Avoid duplicating work. When a document is reused, generate and store it once on the server so it can be reused efficiently, preferably on a cookie-free domain.

Success Criterion: Labels and choice

Resources

Show users the document name, format, size, and a short summary before download. Let users choose the most suitable format and language. Avoid embedding documents directly in pages; instead provide download or browser-view links.

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Tags

Accessibility, Assets, Compatibility, Content, E-Waste, Hardware, Performance, Software, UI, Usability

2.14 Involve users early in the project

Define and validate prototypes and interface components through user testing to ensure they work effectively in real-world use cases and across diverse user needs.

Success Criterion: Early user testing

Resources

Create defined processes for prototyping and testing new features and interface components. Validate them with representative users to ensure they work in real-world conditions and across different needs.

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Tags

Accessibility, Education, Governance, Ideation, Research, Social Equity, Strategy, UI, Usability

2.15 Audit and test for bugs or issues requiring resolution

Regularly audit for issues or problems, running tests at regular intervals in both simulated and real-world scenarios to ensure stability of the project.

Success Criterion: Ongoing evaluation

Resources

Evaluate current user experience and check the codebase for bugs, identify performance issues, and account for accessibility, sustainability, or security problems at appropriate regular intervals, such as every month or quarter.

Success Criterion: Automated tests

Resources

Maintain an automated test suite that covers critical functionality and run it consistently during builds and releases to catch regressions early.

Success Criterion: Performance testing

Resources

Identify and resolve bottlenecks or issues in the underlying code or infrastructure which could impact sustainability and performance to encourage a smooth, frictionless user journey. Consider both simulated and real-world metrics. Monitor performance across every release cycle using appropriate tooling or through research and auditing.

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Tags

Accessibility, Compatibility, KPIs, Performance, Privacy, Reporting, Research, Security, Social Equity, Software, Strategy, UI, Usability

2.16 Validate usability through testing and real-world usage

Monitor user feedback and real usage to evaluate feature effectiveness, and use usability testing and user research to guide ongoing improvements.

Success Criterion: Usage changes

Resources

Monitor user feedback, adoption, and churn for each feature. Use these insights to guide updates and future releases.

Success Criterion: Usability testing

Resources

Use usability testing, real user metrics, and user interviews throughout product development. Measure the impact of findings and check whether released features meet user needs and internal goals.

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Tags

Accessibility, Education, Governance, Ideation, KPIs, Research, Social Equity, Strategy, UI, Usability

2.17 Cross-platform compatibility support

Document compatibility, avoid unnecessary obsolescence, and test across devices, systems, and network conditions.

Success Criterion: Compatibility documentation

Resources

Document supported devices, operating systems, and browsers, including version ranges. Review and update it regularly to reflect current releases.

Success Criterion: Maintaining compatibility

Resources

Avoid planned obsolescence. Keep compatibility for as long as reasonably possible. Clearly explain whether updates are major changes that may affect performance or smaller updates that fix issues or improve security.

Success Criterion: User constraints

Resources

Test for a wide range of user conditions, including slow, restricted or unstable connections, Virtual Private Network (VPN) use, different operating systems and browsers, and older or low-performance devices.

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Tags

Accessibility, Compatibility, KPIs, Research, Security, Social Equity, Software, Strategy, UI, Usability

3. Web Development

Sustainable web design and development practices at the front-end and back-end often intersect with best practices, unlocking numerous benefits for the planet, people, and prosperity alike.

Front-end and back-end web development contribute to a more sustainable web by improving how efficiently projects use resources. Efficient code reduces unnecessary processing and data transfer, lowering the environmental impact of services at scale. These improvements also make projects faster and more reliable, helping them remain usable and maintainable over longer periods. As a result, sustainable web development supports both performance and the long-term viability of digital products.

Goals include:

Benefits include:

Plain language summary of the Web Development:

3.1 Set goals based on performance and energy impact

Define performance and environmental targets, and design content with awareness of the relative energy and processing cost.

Success Criterion: Performance goals

Resources

Set clear performance and environmental goals for the project, including limits on requests, elements rendered, or other measurable resource use.

Success Criterion: Energy intensity

Resources

Prioritize lower-impact design choices, paying attention to measurable differences in energy use across components. Complex structure, styling, and script-driven experiences along with graphics-heavy and media-rich rendering increase the computational complexity of rendering. Use more intensive approaches only where these add clear value.

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Tags

KPIs, Networking, Performance, Research, Social Equity, Strategy

3.2 Minify and remove unused code

Minify code and data, and remove unused characters to reduce file size and improve loading efficiency and maintainability.

Success Criterion: Minified code

Resources

Minify code and data files by removing unnecessary whitespace, comments, and non-essential characters. Apply this consistently across the system to reduce file size and improve loading efficiency. This helps reduce cumulative data transfer and processing overhead at scale, improving resource efficiency and lowering energy consumption.

Success Criterion: Remove redundancy

Resources

Identify and remove unused or dead code, especially in CSS and JavaScript.

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Example

!function(e,t){"use strict";"object"==typeof module&&"object"==typeof module.exports?module.exports=e.document?t(e,!0):function(e){if(!e.document)throw new Error("jQuery requires a window with a document");return t(e)}:t(e)}("undefined"!=typeof window?window:this,function(g,e){"use strict";var t=[],r=Object.getPrototypeOf,s=t.slice,v=t.flat?function(e){return t.flat.call(e)}:function(e){return t.concat.apply([],e)},u=t.push,i=t.indexOf

Tags

Accessibility, CSS, HTML, JavaScript, Performance

3.3 Modularize bandwidth-heavy components

Split large components into smaller, on-demand modules to improve loading efficiency while balancing maintainability and caching performance.

Success Criterion: Code splitting

Resources

Split large or bandwidth-heavy components into smaller modules that load only when needed. Avoid excessive splitting, as it can increase overhead, reduce caching efficiency, and make code harder to maintain.

Additional information

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Example

link.addEventListener("click", (e) => {
	e.preventDefault();
	import("/modules/my-module.js")
	.then((module) => {
		/* Do something */
	})
	.catch((err) => {
		console.error(err.message);
	});
});

Tags

CSS, JavaScript, Performance

3.4 Avoid redundancy and duplication in code

Reduce code duplication through refactoring and reuse, ensure maintainability, and favor evolving existing solutions over rebuilding them.

Success Criterion: Remove or simplify

Resources

Refactor code to reduce duplication and redundancy by improving structure, consolidating repeated logic, and encouraging reuse.

Success Criterion: Iteration over recreation

Resources

Prioritize improving and extending existing user-facing solutions over rebuilding them from scratch. Only replace an existing solution when doing so provides clear benefits to user experience, performance, scalability, or maintainability.

Success Criterion: Organize code arrangement

Resources

Apply DRY (Don't Repeat Yourself) principles to CSS and JavaScript where they improve maintainability. Ensure that efforts to reduce duplication do not increase complexity, introduce unnecessary dependencies, or adversely affect performance.

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Example

.opinions_box {
	margin: 0 0 8px 0;
	text-align: center;
	&__view-more {
		text-decoration: underline;
	}
	&__text-input {
		border: 1px solid #ccc;
	}
	&--is-inactive {
		color: gray;
	}
}

Tags

Accessibility, CSS, JavaScript, Patterns, Performance

3.5 Treat third parties the same as first parties

Minimize and carefully manage third-party services by using lightweight, user-controlled integrations that are loaded only when needed.

Success Criterion: Assess and reduce

Resources

Review third-party content and/or services early in the design or ideation process, including plugins, widgets, feeds, maps, carousels, tracking scripts, and similar components. Use as few as possible, preferring lightweight options to reduce overall environmental impact, including GHG Protocol Scope 3 emissions. Ensure third-party providers enforce the same compliance, security, privacy, data retention limits, data deletion policies, and mandatory security update standards as the first party.

Success Criterion: Third-party implementation

Resources

Load third-party content only when the user interacts with it. Offer simple alternatives, such as linking to a form instead of embedding a widget.

Success Criterion: Self-hosting

Resources

Serve assets such as content, icons, fonts, scripts, and widgets from infrastructure you control where practical, rather than embedding or depending on third-party services for their storage or delivery. This reduces dependency on external systems, improves reliability, and can reduce unnecessary network requests.

Success Criterion: Third-party preferences

Resources

Respect user preferences around third-party content and services. Provide clear controls to disable or opt out of non-essential third-party features.

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Example

<iframe src="https://example.com" loading="lazy" width="600" height="400"></iframe>

Tags

Accessibility, JavaScript, Performance, Privacy, Security, Software, UI, Usability

3.6 Ensure code follows good semantic practices

Use standards-compliant HTML and web platform features, and avoid unnecessary complexity or non-standard code.

Success Criterion: Semantic code

Resources

Use valid and standards-compliant markup.

Success Criterion: Optional features

Resources

Remove optional HTML elements, attribute quotes, and default attributes if doing so does not negatively impact accessibility, readability, functionality, or performance. Include them when they improve accessibility, maintain clarity without compromising performance, or ensure consistent browser rendering.

Success Criterion: Non-standard code

Resources

Avoid deprecated, proprietary, or non-standard technologies unless there is a clear, justified need such as legacy compatibility or accessibility. Use polyfills only when necessary and review them regularly for removal.

Success Criterion: Custom code

Resources

Use standard HTML elements, attributes, features, and APIs wherever they meet the requirement. Use custom elements, Web Components, or custom functionality only when built-in web platform capabilities cannot meet the need or when building reusable design system components.

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Example

<button onclick="window.dialog.showModal();">open dialog</button>
<dialog id="dialog">
	<p>I'm a dialog.</p>
	<form method="dialog">
		<button>Close</button>
	</form>
</dialog>

Tags

Accessibility, Compatibility, Content, HTML, Security, Social Equity, Usability

3.7 Defer the loading of non-critical resources

Load non-essential assets asynchronously or with prioritization to improve rendering performance and avoid visual issues.

Success Criterion: Asynchronous code

Resources

Load non-essential external assets asynchronously or defer them to avoid rendering issues such as Flash Of Unstyled Content (FOUC), Flash of Invisible Text (FOIT), or Flash of Faux Text (FOFT).

Success Criterion: Optimized loading

Resources

Use resource and priority hints to improve loading performance when multiple assets compete for bandwidth or rendering order.

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Example

<link rel="prefetch" href="/articles/" as="document">

Tags

Accessibility, Assets, CSS, JavaScript, Performance

3.8 Structure metadata for machine readability

Include essential document metadata and structured data to improve usability, accessibility, and machine readability.

Success Criterion: Required elements

Resources

Include a required title element and add optional HTML head elements where they improve usability, accessibility, or performance.

Success Criterion: Meta tags

Resources

Include relevant meta tags that are widely used by browsers, search engines, and other user agents.

Success Criterion: Structured data

Resources

Use structured data, such as schema.org, implemented with JSON-LD, microdata, RDFa, or microformats, to enable consistent interpretation and reuse of content by both humans and machines across tools and services.

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Example

<html>
	<head>
		<title>Example: A website about Examples</title>
		<script type="application/ld+json">
		{
			"@context" : "https://schema.org",
			"@type" : "WebSite",
			"name" : "Example",
			"url" : "https://example.com/"
		}
	</script>
	</head>
	<body>
	</body>
</html>

Tags

Accessibility, AI, HTML, Marketing, Usability

3.9 Use media queries that support sustainability goals

Support user preferences via media queries for color, motion, contrast, data use, and related settings to improve accessibility and efficiency.

Success Criterion: Media and preference queries

Resources

Accommodate common user preferences using CSS media queries such as prefers-color-scheme. Account for additional preference queries, including monochrome, prefers-contrast, prefers-reduced-data, prefers-reduced-transparency, and prefers-reduced-motion where these will benefit your users. Use print and scripting media queries where they can improve efficiency or sustainability.

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Example

@media (prefers-color-scheme: dark) {
	/* wants dark mode */
}
@media (prefers-color-scheme: light) {
	/* wants light mode */
}

Tags

Accessibility, Assets, CSS, UI, Usability

3.10 Ensure layouts work for different devices and requirements

Use responsive, progressively enhanced, and carbon-aware design to ensure accessible, adaptable functionality across devices and interaction methods while managing resource use.

Success Criterion: Device-adaptable

Resources

Use responsive and adaptive design so the product works across devices and screen sizes such as phones, tablets, laptops, desktops, TVs, and emerging platforms. Ensure the project still functions when certain features or technologies are not supported.

Success Criterion: Progressive enhancement

Resources

Use progressive enhancement to enhance sustainability by starting with a baseline of HTML, then progressively improving the user experience without relying on style or interaction for core functionality, ensuring a robust and resilient project.

Success Criterion: Carbon-aware design

Resources

Use carbon-aware design to reduce energy use when electricity demand or system load is high. Use situational design to replace, reduce, or disable high-impact features for lower-impact alternatives. Automated thresholds may also adjust or disable non-essential features, provided changes remain transparent. Clearly communicate what changed and why, and allow users to restore full functionality where possible.

Success Criterion: Alternative browsing

Resources

Support sustainable non-visual and indirect interaction methods such as assistive technologies, voice input, QR codes, reader view (browser, application, or RSS), and connected devices.

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Example

@media screen and (min-width: 600px) {
	body {
		color: red;
	}
}

Tags

Accessibility, AI, Compatibility, Content, CSS, Performance, Social Equity, UI, Usability

3.11 Use sustainable JavaScript and APIs

Write efficient JavaScript and use APIs that minimize processing, data use, and energy consumption.

Success Criterion: Sustainable JavaScript

Resources

Write JavaScript that supports long-term application performance by reducing unnecessary calculations, limiting DOM updates, and minimizing network requests.

Success Criterion: Energy-relevant APIs

Resources

Leverage JavaScript APIs, such as Compression Streams, Page Visibility, or Vibration, when they help reduce energy use or improve efficiency.

Success Criterion: API requests

Resources

Only call client-side or server-side APIs when needed. Ensure only data required for the task is included in requests and responses.

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Example

const audio = document.querySelector("audio");
// Handle page visibility change:
// - If the page is hidden, pause the video
// - If the page is shown, play the video
document.addEventListener("visibilitychange", () => {
if (document.hidden) {
	audio.pause();
} else {
	audio.play();
}
});

Tags

Accessibility, JavaScript, Privacy, Security

3.12 Use dependencies sparingly and maintain them

Regularly review dependencies, remove unused or unnecessary libraries and frameworks, and keep required packages up to date. Opt for minimal, secure, and modular solutions.

Success Criterion: Dependency management

Resources

Review dependencies regularly and remove unused libraries and frameworks. Uninstall packages that are not needed.

Success Criterion: Dependency necessity

Resources

Limit the use of external libraries and frameworks to what is necessary, as this reduces the amount of code that must be downloaded and parsed by the browser. Prioritize plain code where possible. Review package size and evaluate whether individual modules can be imported instead of entire libraries, or whether a more performant alternative can be used. Do not replace established and trusted security libraries with custom implementations, as this increases vulnerability and can negatively impact sustainability.

Success Criterion: Dependency updates

Resources

Keep all dependencies up to date through regular review and maintenance.

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Example

npm uninstall <package-name>

Tags

Accessibility, JavaScript, Patterns, Performance, Privacy, Security, Software

3.13 Include expected and beneficial files

Include standard website metadata and configuration files to support discoverability, transparency, and operational best practices.

Success Criterion: Expected files

Resources

Include favicon.ico, robots.txt, opensearch.xml, site.webmanifest, and sitemap.xml by default. Include additional default files if they become standard.

Success Criterion: Beneficial files

Resources

Include additional standard files, such as ads.txt, carbon.txt, humans.txt, and security.txt. Include additional default files if they become standard.

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Example

The below is a robots.txt formatted file.

User-agent: *
Disallow: /cgi-bin/

Tags

Accessibility, Assets, Compatibility, Marketing, Patterns, Security, UI

3.14 Use the most efficient solution for your service

Choose lightweight, efficient implementation approaches that balance effort, performance, and environmental impact while favoring simple, native, and static solutions.

Success Criterion: Appropriate Implementation

Resources

Choose implementation approaches that balance effort, performance, and environmental impact. Simpler solutions may reduce complexity and runtime impact but require more human effort, while prebuilt tools may reduce build time and development effort but increase ongoing resource use.

Success Criterion: Optimized methodology

Resources

Use the most performant approach for your use case. Most of the time, coding from scratch can provide the most performant results, but where a well-maintained existing solution is available it may be better optimized than what you can produce yourself. Favor native components and file systems over WYSIWYG editors, visual page builders, or heavy frameworks. Be mindful of the performance, maintenance, and environmental impact of third-party solutions.

Success Criterion: Static over dynamic

Resources

Deliver static content in place of dynamic content wherever possible. If code generation is required, favor the efficient tools, such as Static Site Generators (SSGs). Be aware that dynamic CMS-driven content typically involves greater server-side processing and relies on bulkier libraries compared to static approaches.

Success Criterion: Extensions and plugins

Resources

Review plugins, extensions, and themes regularly to ensure they remain compatible with the platform and other components, efficient, and accessible.

Success Criterion: Interface components

Resources

Use user interface components that are lightweight, focused, and efficient, avoiding unnecessary complexity that increases resource use, environmental impact, or maintenance burden.

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Tags

Accessibility, Compatibility, Ideation, Performance, Privacy, Security, Software, Strategy

3.15 Use the latest stable language version

Use up-to-date technologies and select the most suitable programming language for each task to ensure efficiency and maintainability.

Success Criterion: Versioning

Resources

Use the latest stable version of the chosen language and framework.

Success Criterion: Language choice

Resources

Use the best programming language for the task, recognizing that many tools and languages are optimized for specific types of work. Adoption effort is justified where benefits outweigh costs and there is a reasonable user base, provided it does not impact the wellbeing of those involved or become cost-prohibitive.

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Tags

Compatibility, Performance, Security

3.16 Reduce the number and complexity of database queries

Optimize database use by minimizing and scoping queries, reducing repeated requests, and applying data governance practices.

Success Criterion: Efficient database querying

Resources

Optimize database queries to reduce load by retrieving required data in as few queries as possible, and by applying filtering and selection at the database level rather than in application or ORM code, especially for frequently accessed data.

Success Criterion: Reuse of retrieved data

Resources

Retrieve data only once per request or process and reuse it locally instead of repeating database queries.

Success Criterion: Data minimization in queries

Resources

Scope database queries to return only the fields and records that are required.

Success Criterion: Data lifecycle controls

Resources

Apply data lifecycle and governance controls such as Time-to-Live (TTL), use of non-sensitive identifiers like UUIDs, de-identification, and minimization of stored data in line with purpose limitation principles.

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Example

The below is PHP formatted code.

$value = get_post_meta( int $post_id, string $key = '', bool $single = false ): mixed

Tags

Networking, Performance

4. Hosting, Infrastructure, and Systems

Even data has a home. Whether you are developing tools, processing data, maintaining online systems, operating websites or something else - conscious choices that improve sustainability of hosting, infrastructure, and systems can have an enormous impact.

Development operations teams and hosting providers play a key role in ensuring that infrastructure meets performance, reliability, and sustainability requirements. Sustainability depends on decisions about where and how content, code, and data are stored and processed, as these choices affect energy consumption, data transfer distances, and server efficiency. Optimizing infrastructure can reduce unnecessary computational load and improve response times for users, contributing to more efficient and environmentally responsible projects.

Goals include:

Benefits include:

Plain language summary of the Hosting, Infrastructure, and Systems:

4.1 Use sustainable hosting

Select and manage infrastructure using sustainability metrics, prioritizing low-carbon energy use and low-impact hosting and domain choices in selection, and extending hardware lifespan and minimising emissions in management.

Success Criterion: Provider selection

Resources

Include sustainability metrics when selecting and evaluating potential infrastructure, hosting, cloud, platform, externally managed content, or other digital services. Favor providers that publicly and transparently disclose their environmental policies and related performance indicators, including Power Usage Effectiveness (PUE), Water Usage Effectiveness (WUE), Carbon Usage Effectiveness (CUE), renewable energy use, emissions reduction commitments, and hardware maintenance and sourcing practices.

Success Criterion: Efficient operation

Resources

Monitor and reduce the negative environmental impact of all running infrastructure over time. Whether external or self-hosted, track all available relevant indicators, such as energy use, water use, and server resource utilization. This includes CPU/cores, memory, storage, and network usage. Use this information to identify inefficiencies, reduce overprovisioning, optimize resource use, and support transparent sustainability reporting.

Success Criterion: Equipment longevity

Resources

Extend the lifespan of hardware. Use equipment efficiently and at the right capacity and keep it securely patched and properly maintained. New hardware should be sourced from suppliers that commit to device longevity, patching, and repair options..

Success Criterion: Low-carbon electricity

Resources

Use electricity with the lowest possible carbon intensity. Hosting providers should measure and report carbon intensity using available location-based grid data, including on-site generation, backup systems, and storage. Use this information to select lower-carbon hosting providers and improve energy sourcing and infrastructure efficiency.

Success Criterion: Remaining emissions

Resources

Reduce remaining emissions using market-based carbon accounting for indirect electricity emissions under the GHG Protocol (Scope 2). When purchasing low-carbon electricity through Energy Attribute Certificates (EACs) or Renewable Energy Certificates (RECs), ensure the certificates match the time and location of the electricity used, identify when the renewable electricity was generated, can be validly issued and retired in a way that prevents double counting.

Success Criterion: Domain names

Resources

Verify that the impact of domain name registration is disclosed by domain registries and registrars. Where environmental impact data is available from registrars, use it to inform domain registration decisions and mitigate environmental impact. Where such data is unavailable, assess the assumed environmental impact when making registration decisions and make sustainability-focused choices where possible.

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Tags

AI, E-Waste, Hardware, Networking, Social Equity

4.2 Optimize caching and support offline access

Use caching and offline capabilities to reduce network load, improve resilience, and balance performance with sustainability.

Success Criterion: Caching resources

Resources

Use caching to reduce processing time and repeated database queries, API calls, and network requests. Apply server-side caching for dynamic content and client-side caching for resources that do not change frequently. Control cache lifetimes, serve static versions for stable assets, and minimize repeated requests for frequently used resources, balancing against added complexity and maintenance costs to improve how data is delivered.

Success Criterion: Offline access

Resources

Keep essential content and functionality available during network interruptions. Provide offline access using web platform capabilities, such as Progressive Web Applications (PWA), Service Workers, Web Workers, or local storage.

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Example

The below is a .htaccess formatted file.

<IfModule mod_expires.c>
	ExpiresActive on
	# Default: Fallback
	ExpiresDefault                                      "access plus 1 year"
	# Specific: Assets
	ExpiresByType image/x-icon                          "access plus 1 week"
	ExpiresByType application/rss+xml                   "access plus 1 hour"
	ExpiresByType application/json                      "access"
</IfModule>

Tags

Accessibility, Assets, HTML, JavaScript, Networking, Performance, Software

4.3 Reduce data transfer with compression

Compress server responses and media files to reduce bandwidth, storage use, and delivery overhead while balancing processing costs.

Success Criterion: Server-side compression

Resources

Reduce file size before uploading images, audio, and video by using efficient formats and quality settings. Avoid applying additional compression if the file is already appropriately sized for upload.

Success Criterion: Media compression

Resources

Compress media files such as images, video, and audio before uploading anywhere to reduce storage and transfer requirements.

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Example

The below is a .htaccess formatted file.

<IfModule mod_deflate.c>
	<IfModule mod_setenvif.c>
		<IfModule mod_headers.c>
			SetEnvIfNoCase ^(Accept-EncodXng|X-cept-Encoding|X{15}|~{15}|-{15})$ ^((gzip|deflate)\s*,?\s*)+|[X~-]{4,13}$ HAVE_Accept-Encoding
			RequestHeader append Accept-Encoding "zstd, gzip, br, deflate" env=HAVE_Accept-Encoding
		</IfModule>
	</IfModule>
	<IfModule mod_filter.c>
		AddOutputFilterByType DEFLATE "application/atom+xml application/javascript application/json application/ld+json application/manifest+json application/rdf+xml application/rss+xml application/schema+json application/geo+json application/vnd.ms-fontobject application/wasm application/x-font-ttf application/x-javascript application/x-web-app-manifest+json application/xhtml+xml application/xml font/eot font/opentype font/otf font/ttf image/bmp image/svg+xml image/vnd.microsoft.icon image/x-icon text/cache-manifest text/calendar text/css text/html text/javascript text/plain text/markdown text/vcard text/vnd.rim.location.xloc text/vtt text/x-component text/x-cross-domain-policy text/xml"
	</IfModule>
	<IfModule mod_mime.c>
		AddEncoding gzip              svgz
	</IfModule>
</IfModule>

Tags

Assets, Networking, Performance

4.5 Avoid maintaining unnecessary virtualized environments or containers

Remove unnecessary virtualized environments to improve efficiency and maintainability.

Success Criterion: Unused environments

Resources

Reduce the number of active environments by deactivating, offlining, or removing unused or redundant virtual and physical environments (e.g., containers and virtual machines) wherever this can be done without reducing required security, isolation, or compliance guarantees. Also evaluate running services in the same way. Similarly, codebases and setups for unused branches, environments, and services, and remove what is no longer needed.

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Tags

AI, Hardware, Networking, Performance, Software

4.6 Use automation wisely

Automate and scale tasks and infrastructure efficiently, run processes only when needed, and control unwanted traffic.

Success Criterion: Task automation

Resources

Automate recurring tasks such as deployment, testing, and compilation in alignment with continuous integration and continuous delivery (CI/CD) best practices to reduce manual effort and improve consistency. Favor automation tools and platforms with lower environmental impact, and avoid unnecessary duplication of automation systems.

Success Criterion: Necessary tasks

Resources

Run automated tasks only when they are needed to avoid unnecessary resource use.

Success Criterion: Automated scaling

Resources

Use autoscaling to adjust server capacity based on demand. Implement buffering and throttling to manage load pressures. Scale resources up during high demand and scale down when demand drops to avoid overprovisioning.

Success Criterion: Suspicious activity management

Resources

Restrict unwanted and unnecessary third-party crawlers, user agents, bots, and scrapers using security controls, while ensuring content remains accessible to legitimate users, search engines, and helpful or authorized crawlers. Take into account that some scrapers may be used for beneficial purposes, including informing or training large language models.

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Tags

Accessibility, AI, Performance, Security, Software

4.7 Define the frequency of data refreshes

Decide when to refresh data based on a balance of user and sustainability requirements.

Success Criterion: Refresh frequency

Resources

Define cache refresh rates based on user needs, accuracy requirements, and resource efficiency to determine when data is updated.

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Tags

JavaScript, Networking, Performance, Usability

4.8 Back up critical data at routine intervals

Back up data at regular intervals to ensure that there are failsafes that can be relied upon should an issue occur.

Success Criterion: Data backups

Resources

Ensure backups of systems and user data are secure and incremental to minimize storage use and reduce backup time. Limit access to backups, and establish mechanisms to prevent user-identifiable information from being stored long term. Protect backups against data loss or misuse.

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Tags

Hardware, Performance, Security

4.9 Assess the impact and requirements of data processing

Use carbon-aware scheduling, efficient and secure protocols, and simple system designs to reduce unnecessary processing while balancing performance, security, and constraints.

Success Criterion: Carbon shifting

Resources

Use carbon-aware computing to dynamically optimize workload execution by scheduling or batching tasks to run at a time when carbon intensity is lower based on real-time grid carbon intensity data, or shifting workloads to regions with lower carbon intensity when possible, while respecting security, performance, and data residency constraints.

Success Criterion: Protocol efficiency

Resources

Choose communication protocols that balance user needs, security, and sustainability by improving efficiency and reducing resource use. Prioritize secure options like HTTPS and SFTP/SSH, avoid insecure legacy protocols such as HTTP and FTP, and adopt modern standards like HTTP/2 or HTTP/3 for better performance and lower network overhead. Maintain backward compatibility only where necessary.

Success Criterion: Event-driven architecture

Resources

Use event-driven architecture and microservices when building products with state changes that do not require full page refreshes. Favor those where they offer a more energy-efficient alternative to REST-style synchronous APIs based on performance, power, and processing factors, and choose the approach that reduces server workload and environmental impact while meeting requirements.

Success Criterion: Data processing efficiency

Resources

Avoid unnecessary data processing. Decide carefully whether processing should happen on the client or server based on performance, security, sustainability metrics, and resource use.

Success Criterion: Efficient location

Resources

Perform data transformations, transfers, and processing between the layers of an application as close to the source as possible. This reduces unnecessary serialization overhead and avoids wasting resources.

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AI, JavaScript, Networking, Performance

4.10 Use Content Delivery Networks (CDNs) when beneficial

Use CDNs and data location strategically for static content and processing only when they improve efficiency and sustainability, while avoiding unnecessary distribution and transfers.

Success Criterion: Global CDNs

Resources

Use a Content Delivery Network (CDN) for static content, assets, and other read-only resources only where it provides clear benefits, evaluating performance improvements and environmental impact on a case-by-case basis in line with broader web hosting choices. When serving an exclusively local audience, evaluate whether a CDN is necessary, and prefer geographically close hosting instead.

Success Criterion: Sustainability commitment

Resources

Choose CDN providers that demonstrate credible, evidence-based web sustainability commitments.

Success Criterion: Inappropriate resources

Resources

Avoid deploying dynamic or frequently changing resources to a CDN, as browser mechanisms like cache partitioning and cross-origin resource sharing (CORS) can limit caching benefits and interaction performance, reducing resource efficiency, while workarounds may introduce security or privacy risks.

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Accessibility, AI, Content, Hardware, Networking, Performance

4.11 Ensure infrastructure fits project requirements

Use demand-matched, autoscaling infrastructure to meet demand efficiently without overprovisioning.

Success Criterion: Lowest requirements

Resources

Select infrastructure that meets your requirements and customer agreements without over-provisioning. Favor standalone instances over multi-zone or distributed setups when requirements allow. Provision for average loads rather than peak loads to ensure efficient resource use.

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E-Waste, Hardware, Performance

4.12 Store data according to the needs of your users

Regularly manage and reduce stored data (including content, logs, media, and downloads) using retention, compression, and lifecycle policies, while maintaining efficient access to long-term assets.

Success Criterion: Remove unused data

Resources

Regularly remove unused or obsolete data ("dark data") to reduce storage and energy costs, and manage whether and how long data is stored.

Success Criterion: Lifecycle management

Resources

Use classification and tagging policies to define and manage data lifecycle rules, including retention, expiration, and archival.

Success Criterion: Efficient storage

Resources

Store data only where it provides lasting operational, analytical, or legal value and cannot be easily regenerated or replaced. Remove or archive it when it becomes obsolete. Avoid unnecessary duplication and use efficient storage practices such as compression, caching, and storage optimization techniques.

Success Criterion: Optimized logging

Resources

Manage logs with regular rotation, retention, compression, and backup practices, including scheduling resource-intensive operations during low-activity periods where practical to reduce energy demand and operational overhead. Use resilient backup strategies, including off-site storage when necessary for resilience or recovery, and remove sensitive information from logs wherever possible to minimize security and privacy risks.

Success Criterion: Asset downloads

Resources

Make large, long-term assets easily downloadable so users do not need repeated server requests.

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Accessibility, Content, E-Waste, Hardware, Performance, Privacy

5. Business Strategy and Product Management

Designing websites and applications for better sustainability requires good business strategy and product management.

Anyone responsible for a website or application can influence its environmental impact. Business owners and senior decision-makers are often responsible for strategic choices that shape how services are built, delivered, and maintained, including investment in infrastructure, performance priorities, and long-term product direction. However, all individuals working on digital products can contribute through day-to-day decisions that improve efficiency and reduce unnecessary resource use. These efforts also connect to wider organizational practices that influence a projects web sustainability.

Goals include:

Benefits include:

Plain language summary of the Business Strategy and Product Management:

5.1 Have an ethical and sustainable product strategy

Implement organizational practices around ethics, sustainability, and responsible data use. Publish and maintain policies that demonstrate their implementation.

Success Criterion: Public documents

Resources

Develop, publish, and maintain key organizational policies such as a code of ethics, product guidelines, accessibility, and sustainability statements. Include clear language for digital products, services, and emerging or disruptive technologies, such as AI. Make these policies publicly accessible and keep them versioned for transparency.

Success Criterion: Achievements and compliance

Resources

Publish web sustainability-related achievements, features, compliance updates, and other relevant information within a dedicated sustainability section.

Success Criterion: Governance over time

Resources

Provide evidence that sustainability policies and practices are actively implemented, monitored, and governed over time.

Success Criterion: Technology legislation

Resources

Advocate for and comply with evidence-based legislation and standards that advance digital privacy, employment rights, transparency, accountability, responsible emerging technologies, and digital sustainability. Simultaneously make efforts to go beyond minimum expectations, especially in regard to avoiding unnecessary data collection to preserve an efficient and accessible user journey in compliance with accessibility and data protection requirements.

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Accessibility, AI, Education, Ideation, KPIs, Privacy, Research, Security, Social Equity, Strategy

5.2 Assign a sustainability advocate

Appoint a sustainability advocate who is provided with what they require to speak about and for issues relating to sustainability.

Success Criterion: Advocate for sustainability

Resources

Assign clear responsibility for digital sustainability by appointing a sustainability lead with specific digital expertise and providing them with the resources, budget, tools, and time they need to achieve their stated goals. In some organizations, expanding this into a climate working group comprising motivated individuals can add further benefits.

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Accessibility, Education, Ideation, Marketing, Privacy, Social Equity

5.3 Inform, raise awareness, and train for sustainability

Provide ongoing training, onboarding, and guidance on sustainability practices, and support participation in sustainability initiatives through clear materials, knowledge sharing, and organizational encouragement.

Success Criterion: Inform and aware

Resources

Produce, provide, and/or facilitate the delivery of onboarding materials and workshops to everyone connected to your project, including internal teams, external contributors, colleagues, and organizational decision-makers. Include education on general and digital climate literacy, as well as guidance on your own sustainable technology policies.

Success Criterion: Routine training

Resources

Provide active and routine training to develop, establish, and refresh sustainability skills through ongoing learning opportunities that support teams in achieving sustainability objectives.

Success Criterion: Active participation

Resources

Encourage individuals to reduce their environmental impact. Share climate and sustainable initiatives and ideas. Provide resources on sustainable design, best practices, and concepts.

Success Criterion: Training materials

Resources

Create and/or deliver dedicated training manuals, workshops, and materials to outline the adopted sustainability policies and practices and how to implement them. Manage and maintain these materials over time, adapting them as new policies and best practices arise.

Success Criterion: Incentivize progress

Resources

Encourage leadership, teams, and individuals to make progress toward their training goals by recognizing completion, allocating time for sustainability-related activities, and providing incentives and benefits.

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Content, Education, Marketing, Reporting

5.4 Communicate the environmental impact of user choices

Empower users, allowing them to make decisions when their choices can influence the environmental impact they have.

Success Criterion: Communication of impact

Resources

Show users how their actions affect energy use, emissions, or resource consumption, and provide options that help them make more informed choices.

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Content, Education, Marketing, Reporting

5.5 Calculate the environmental impact

Assess and compare full life cycle environmental impacts, including those of third-party services, to inform sustainable design decisions.

Success Criterion: Life-cycle assessment

Resources

Conduct a life cycle assessment (LCA) to understand the environmental impact of each functional unit - a defined measure of a product or service being assessed - including lifecycle greenhouse gas (GHG) emissions and other relevant environmental impacts across the full project lifecycle.

Success Criterion: Competitor impact

Resources

Evaluate the environmental impact of your project against comparable alternatives to inform decision-making targets. Determine whether the project's additional value or sustainability benefits justify its environmental impacts.

Success Criterion: Tooling impact

Resources

Include the impact or estimated impact of any tooling or third-party solutions used at any stage in your pipeline. While not created by you, the emissions generated in production, maintenance, and use are also integral to your overall solution.

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Accessibility, AI, Ideation, KPIs, Research, Social Equity, Software, Strategy

5.6 Define clear organizational sustainability goals and metrics

Define measurable sustainability goals and metrics, and communicate progress over time.

Success Criterion: Web sustainability goals

Resources

Define and publish clear web sustainability goals. Identify measurable performance metrics and communicate progress against those goals so that people can understand and evaluate sustainability performance.

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AI, Governance, Ideation, KPIs, Research, Social Equity

5.7 Validate web sustainability efforts through external verification

Use independent verification to support and improve sustainability claims.

Success Criterion: Obtaining verification

Resources

Use independent third-party verification or assurance to validate sustainability claims.

Success Criterion: Maintaining verification

Resources

Reassess sustainability claims over time and update them when new evidence affects their accuracy.

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Governance, KPIs

5.8 Support mandatory disclosures and reporting

Publish transparent, standards-aligned sustainability reports that track progress over time and clearly explain real impact reductions without misleading reporting.

Success Criterion: Policies and practices

Resources

Create and publish policies and practices for disclosing the environmental, social, and governance impacts of digital products, programs, and services in line with recognized standards.

Success Criterion: Impact reports

Resources

Publish a public sustainability impact report at least annually, including progress against previous reports and web sustainability goals.

Success Criterion: Disclosure reporting

Resources

Create and maintain transparent reporting practices for the emissions and the environmental, social, and governance impacts of digital products and web services.

Success Criterion: Impact reduction

Resources

Clearly explain how the environmental, social, and governance impacts are reduced, while avoiding misleading practices such as double counting, greenwashing, data exclusion, or selective reporting.

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AI, Content, KPIs, Reporting

5.9 Create one or more impact business models

Describe how revenue generation supports environmental and social outcomes.

Success Criterion: Theory of change

Resources

Document how the organization generates revenue and how those revenue streams relate to environmental and social impacts. Describe how impacts are measured, reviewed, and improved over time.

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Content, Ideation, Research, Strategy

5.10 Follow a product management and maintenance strategy

Maintain clear documentation, resourcing, and measurement practices for long-term product support, including security, sustainability, and early detection of failure risks.

Success Criterion: Management and maintenance

Resources

Produce and maintain documentation to outline how the organization approaches product management and maintenance.

Success Criterion: Planning Strategy

Resources

Develop, implement, and maintain maintenance and security plans for all digital products and services that prioritize long-term sustainability, energy efficiency, and responsible resource use across the product lifecycle.

Success Criterion: Resourcing products

Resources

Ensure products, prototypes, testing, and supporting processes are adequately resourced over time. Maintain sufficient staffing and budget to support ongoing maintenance, including addressing technical debt, refactoring, and evolving functionality, without abandoning projects.

Success Criterion: Resource measurement

Resources

Include carbon and resource measurement in maintenance processes, and track improvements over time. Prioritize metrics that reflect essential value delivered and sustainability outcomes. Avoid metrics that incentivize unnecessary work, resource consumption, or emissions.

Success Criterion: Failure indicators

Resources

Identify and document Key Failure Indicators (KFIs), including those related to accessibility, usability, and other environmental, social, and governance impacts. Monitor KFIs to detect emerging risks and inform corrective action.

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Accessibility, Compatibility, Security, Strategy

5.11 Implement continuous improvement procedures

Maintain continuous improvement processes that balance feature changes, maintenance, and updates with user value and sustainability outcomes.

Success Criterion: Continuous improvement

Resources

Embed continuous improvement practices that clearly report what is changing, why it is changing, and whether it improves environmental sustainability outcomes. Ensure that environmental and other ESG impacts are assessed alongside operational and business performance metrics.

Success Criterion: Retrospectives conducted

Resources

Review deliverables and update frequently to ensure project teams have enough time to conduct user research, identify and eliminate technical debt, and produce high-quality output as well as share what they learned.

Success Criterion: Iterative consideration

Resources

Display a track record of continuous improvement (iteration) processes to analyze the digital product or service. Simultaneously address any potential consequences of ongoing experimentation, such as technical debt, product performance, and emissions. Limit analytics to strictly necessary features that aid decision-making, encouraging user feedback, and comparing performance against organization goals and user needs.

Success Criterion: Functionality decisions

Resources

Regularly review all functionality across the product lifecycle. Justify and prioritize decisions to retain, change, add, or remove features based on environmental impact, user value, usage, and maintenance cost. This includes decommissioning unused or low-traffic functionality and content.

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Accessibility, AI, Compatibility, KPIs, Performance, Privacy, Security, Strategy, UI

5.12 Document updates and evolutions

Provide documentation to help users find their way whenever functionality changes.

Success Criterion: Feature changes

Resources

Provide clear, structured documentation when features are added, changed, or removed. Use a consistent versioning or change-tracking system to communicate the nature and impact of changes.

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Example

The below is a change.log plain text file.

# Changelog - Website

## [Unreleased]
- N/A

## 1.0.0 - YYYY-MM-DD
### Added
- Content.

## [Guide]
- Added: New features.
- Changed: Altered functionality.
- Deprecated: Disappearing features.
- Removed: Eliminated features.
- Fixed: Bugs patched.
- Security: Solved vulnerabilities.

Tags

Compatibility, Content, Education, Security, Usability

5.13 Evaluate if a digital product or service is necessary

Assess alignment with sustainability goals, validate product need, and reduce barriers to access, usability, and fairness.

Success Criterion: Sustainable Development Goals

Resources

Identify whether the product or service aligns with any relevant UN Sustainable Development Goals (U.N. (SDG) and, where applicable, include corresponding targets within a sustainability statement.

Success Criterion: Creation evaluation

Resources

Evaluate whether a product or service is needed based on desirability, feasibility, and viability.

Success Criterion: Obstacle consideration

Resources

Remove or reduce barriers that prevent people from using a product or service, including accessibility, technical, geographic, and fairness-related barriers.

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Accessibility, AI, E-Waste, Ideation, Reporting, Software

5.14 Provide a supplier standards of practice document

Select and work with suppliers based on sustainability principles, measure their impact, and transparently publish partnership outcomes.

Success Criterion: Vetting potential partners

Resources

Apply sustainability principles across supply chain partner selection and governance, supported by clear policies for vetting and assessing potential partners.

Success Criterion: Collaborative measurement

Resources

Partner with suppliers to create, track, and measure impacts on affected parties.

Success Criterion: Informative partner promotion

Resources

Promote and disclose partnerships in a publicly available place, along with information on how the partnership creates a collective impact.

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AI, Content, Governance, Hardware, Ideation, Social Equity

5.15 Share economic benefits

Commit to fair pay, align workers and contractors with shared impact goals, and provide employee benefits within available resources.

Success Criterion: Living wage

Resources

Publicly commit to paying employees, contractors, and other affected parties a living wage.

Success Criterion: Incentivisation

Resources

Embed incentives for affected parties such as workers and contractors into organizational practices to support impact goals, underpinned by clear policies that guide how incentives are designed and applied.

Success Criterion: Employee benefits

Resources

Provide employee benefits that match available resources, which may include healthcare, retirement support, flexible working, and profit sharing.

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Governance, Social Equity

5.16 Share decision-making power with affected parties

Involve users and staff in decision-making, ensure human oversight, and provide transparency, and challenge mechanisms for automated decisions.

Success Criterion: Decision-making

Resources

Involve people, including users and staff, in decisions that impact them. Provide meaningful opportunities to participate in relevant decision-making processes and ensure decision-makers have clear authority and accountability. Where automated systems are used, provide transparency about their role in decisions, enable human oversight, and allow people to opt out, object, withdraw their consent, and challenge decisions. Ensure challenges are reviewed by a human decision-maker.

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Accessibility, Ideation, Social Equity, Strategy

5.17 Use Diversity, Equity, Justice, Inclusion (DEJI) practices

Publish and act on Diversity, Equity, Justice, Inclusion (DEIJ) and accessibility commitments, support training and measurable progress, and ensure inclusive outcomes across products and operations.

Success Criterion: DEJI practices

Resources

Publish clear commitments to DEIJ. Explain how the organization applies these commitments to reduce exclusion and support the long-term sustainability of access to the product for diverse and underserved or marginalized communities.

Success Criterion: DEJI training

Resources

Provide DEIJ training and topics such as algorithmic bias, the digital divide, employment equity, mis- and disinformation.

Success Criterion: DEJI improvements

Resources

Track and publish measurable progress in DEIJ across hiring, leadership, and operations.

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Accessibility, Ideation, Social Equity, Strategy

5.18 Promote responsible data practices

Respect user data rights and manage data lifecycle through minimized collection, user control, portability, deletion, and content archiving.

Success Criterion: Data practices

Resources

Maintain publicly accessible privacy, legal, and policy documents in plain language and accessible formats. Follow strong data protection practices aligned with recognized international standards, apply stronger protections where risks to users are higher or safeguards are insufficient, and support good practices in privacy, accessibility, and sustainability through transparent data use and governance.

Success Criterion: Data ownership

Resources

Respect user data rights, including access, correction, deletion, opt-out, and data portability. Provide clear user controls to manage accounts, data, and subscriptions. Only collect and retain personal data for a defined purpose and for no longer than necessary. Provide data export in open, commonly used formats. Ensure that deletion and consent changes apply across all systems, including databases, derived datasets, backups, and caches, within a reasonable timeframe.

Success Criterion: Outdated content

Resources

Archive and delete outdated or otherwise expired product content and data via automated expiration dates and scheduled product audits. Publish the archiving schedule, ensuring a lightweight version of the old searchable content is maintained for those that may require it.

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AI, Content, Governance, Privacy, Security, Social Equity, Strategy

5.19 Establish responsible practices around AI and emerging or disruptive technologies

Ensure responsible use of automated systems by only using ethically sourced and suitably sized data and models, managing environmental impacts, supporting workforce adaptation, respecting user agent controls, and using post-quantum encryption only where justified.

Success Criterion: AI and data collection

Resources

Ensure datasets used, created, or referenced by automated systems are no larger than necessary for the task, ethically sourced, screened, validated, stored, and used in a fair and non-discriminatory, responsible way.

Success Criterion: Business adaptation

Resources

Support employees in adapting to new technologies that may change or disrupt their roles or the organization's operations.

Success Criterion: Environmental responsibilities

Resources

Audit and account for environmental impacts linked to the promotion or adoption of AI and emerging or disruptive technologies. This includes third-party systems and the waste, water, and emissions generated per use, as well as those resulting from initial deployment and updates. Prioritize efficiency and deployment in a way that minimizes environmental impacts.

Success Criterion: Automated tooling

Resources

Ensure bots, crawlers, user agents, scrapers, artificial intelligence, and all other automated tools respect opt-out signals at the host, server, and site level. Providers must declare themselves as non-human within the user agent in the HTTP header.

Success Criterion: Quantum resilience

Resources

Use post-quantum encryption only where there is a clear need to protect against “harvest now, decrypt later” attacks and long-term data confidentiality risks. Treat it as supplementary to rather than replacing existing encryption methods, using both during any transition. Apply caution when adopting post-quantum encryption in high-traffic services, as the bandwidth consumption, processing demand, design complexity, and migration risks may outweigh the security benefits.

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Accessibility, AI, Content, E-Waste, Governance, Hardware, Networking, Performance, Privacy, Security, Social Equity, Software

5.20 Adopt responsible financial practices

Adopt responsible financing practices by divesting from high-carbon assets and aligning budgeting and financial partnerships with long-term sustainability.

Success Criterion: Fuel divestment

Resources

Divest from fossil fuels and move financial relationships, including banking and sponsorships, toward more sustainable partners.

Success Criterion: Responsible finance

Resources

Use responsible budgeting and financing practices that support long-term maintenance and environmental responsibility.

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Governance, Ideation, Social Equity

5.21 Adopt organizational philanthropy practices

Align partnerships and corporate giving with the organization's purpose, and support skill-building voluntary and pro bono work through clear partnership and giving policies.

Success Criterion: Philanthropy policy

Resources

Create a corporate giving policy and establish philanthropic partnerships with strategically aligned organizations.

Success Criterion: Voluntary work

Resources

Support voluntary and pro-bono work that helps teams learn and benefits non-profit and charitable organizations.

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Content, Governance, Social Equity

5.22 Plan for a digital product or service's care and end-of-life

Document when a project is shut down and make users aware of what will happen to their data.

Success Criterion: End-of-life care

Resources

Provide clear, documented end-of-life guidelines that include data disposal, archiving, file deletion, and other relevant guidance.

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Compatibility, E-Waste, Privacy, Research, Security, Social Equity, Software, Strategy

5.23 Repair, reuse, refurbish, recycle or reduce e-waste

Prioritize repair, reuse, refurbishment, and responsible recycling of hardware and e-waste through certified services, including supporting users doing repairs.

Success Criterion: E-waste management

Resources

Recycle, repair, or upcycle unwanted hardware and materials. Recover, redeploy, and reuse components where possible, and dispose of remaining materials in a sustainable way. Use certified repair and recycling services to handle end-of-life digital equipment and operational e-waste responsibly. Service providers should maintain a clear policy for responsible e-waste management.

Success Criterion: E-waste policy

Resources

Maintain policies for repairing and recycling hardware and encourage repair.

Success Criterion: Refurbishment strategy

Resources

Prioritize reuse, refurbishment, and redeployment of existing hardware before purchasing new equipment.

Success Criterion: Right to repair

Resources

Allow users to repair purchased products to the best of their ability, provide replacement parts at cost where possible, and give clear instructions to help fix faults when they occur.

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Content, E-Waste, Governance, Hardware, Ideation, Social Equity

5.24 Define performance, environmental, and human budgets

Define and apply lifecycle sustainability and performance budgets, set evidence-based KPIs, and track measurable improvements over time.

Success Criterion: Environmental budget

Resources

Outline and document digital sustainability budget criteria covering the full lifecycle of products and services, including creation, usage, and decommissioning. Ensure these limits are actively applied and communicated to all affected parties.

Success Criterion: Performance budget

Resources

Use performance budgets to cap the size and complexity of digital products or services, actively reducing data transfer and file sizes to improve performance and create more sustainable, lower-impact digital experiences.

Success Criterion: Human budget

Resources

Define KPIs for engineering effort, development time, or sprints. Optimize workflows sustainably so work is done with care, while prioritizing worker health, wellbeing, and sustainable workloads.

Success Criterion: Measurable improvements

Resources

Establish baseline measurements and track improvements over time. Require that improvement claims are supported by evidence.

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Example

The below is a JSON formatted file.

[
{
	"resourceSizes": [],
	"timings": [
	{
		"metric": "largest-contentful-paint",
		"budget": 2500
	},
	{
		"metric": "max-potential-fid",
		"budget": 100
	},
	{
		"metric": "cumulative-layout-shift",
		"budget": 0.1
	}
	]
}
]

Tags

Accessibility, Ideation, KPIs, Performance, Research, Usability

5.25 Use and contribute to open source

Define and maintain an open-source policy and actively contribute to open-source communities through code, time, and financial or in-kind support.

Success Criterion: Open source governance

Resources

Define and maintain processes for the sustainable use and contribution of open-source tools, including selection, approval, and release workflows that prioritize reuse, reduce duplication, and support long-term maintainability.

Success Criterion: Collaboration and contribution

Resources

Collaborate with the open-source ecosystem to support sustainable software development, grounded in open-source principles, and contribute regularly to community-based projects through code, time, or financial support to improve shared maintenance, reuse, and reduce duplication of effort.

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Accessibility, Assets, Ideation, Social Equity, Software, UI

5.26 Create a business continuity and disaster recovery plan

Maintain tested incident response plans and communicate transparently with users about service issues, risks, and recovery.

Success Criterion: Plan of action

Resources

Create, maintain, regularly review, and test incident response plans to determine readiness and ensure systems and services can quickly recover from any incident.

Success Criterion: Audience awareness

Resources

Communicate transparently with users about incidents, service issues, and any risks to data or availability.

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AI, Governance, Security, Strategy

A. Considerations

Guidelines within this specification which the Interest Group has identified possible implications for accessibility, privacy, or security, either by providing protections for end users or which are important for website providers to take in to consideration when implementing features designed to implement digital sustainability, are listed below. This list reflects the current understanding of the Interest Group but other guidelines may have implications that the Interest Group is not aware of at the time of publishing.

Individuals or organizations wishing to understand more about best practices relating to these objectives should read the relevant materials provided by W3C Working and Interest Groups in this area, as the result of good accessibility, internationalization, privacy, and security, can benefit the planet, people, and prosperity in measurable ways.

It is relevant to note that groups working on accessibility, internationalization, privacy, and security may identify sustainability impacts within their work and may provide relevant guidance where appropriate on best practices to limit the scope of these concerns. Any such guidance should be considered as complementary to that provided within WSG.

Note: Greenwashing should be treated seriously as a consideration, as misrepresenting societal impacts can undermine digital inclusion, security, and privacy. Moreover, these risks and impacts may themselves be exploited as vectors for environmental or broader societal harm.

A.1 Accessibility

Guidelines within this specification that may relate to accessibility are:

A.2 Privacy

Guidelines within this specification that may relate to privacy are:

A.3 Security

Guidelines within this specification that may relate to security are:

B. Glossary

Accessibility

Web accessibility (within the context of inclusive design) means that websites, tools, and technologies are designed and developed so that people with disabilities (and those without) can use them, free of barriers.

Note

Types of accessibility barriers can include auditory, cognitive, neurological, physical, speech, and visual. They can also be permanent, temporary, or situational (depending on the situation).

PPP

Planet, People, and Prosperity (PPP) is a set of principles that recommends considering each of these factors during the sustainability process.

This method of considering the planet, people, and prosperity is known under other abbreviations with similar objectives such as Environmental, Social, and (corporate) Governance (ESG), which considers economic factors alongside; there is also Environment, Equity, and Economy (EEE) that follow a similar pattern.

Informative

For information purposes and not required for compliance.

Note

Content identified as "informative" or "non-normative" is never required for compliance.

Normative

Required for compliance.

C. Acknowledgments

Additional information about participation in the Sustainable Web Interest Group can be found within the GitHub repository of the Interest Group.

C.1 Participants active in the development of this document

Adam Newman, Addison Phillips, Alexander Dawson, Alisa Bonsignore, Andrea Davanzo, Andrew Wright, Andy Blum, Anne Faubry, Arnaud Levy, Barry Pollard, Ben Clifford, Berwyn Powell, Bhavani Shankar Garikapati, Brett Tackaberry, Brian Louis Ramirez, Brian Kardell, Chris Adams, Chris Augier, Chris Butterworth, Chris Lilley, Chris Needham, Chris Sater, Chris Wilson, Christian H Brown, Claire Thornewill, Crystal Preston-Watson, Daniel Appelquist, David Jeanmonod, Denis Roio, Dennis Lemm, Diogo Abrantes Da Silva, Dominique Hazael-Massieux, Dom Robinson, Elika Etemad, Eloisa Guerrero, Emily Trotter, Emma Horrell, Fershad Irani, Florian Rivoal, Francesco Fullone, François Burra, Gaël Duez, Glenda Sims, Hannah Smith, Hidde de Vries, Iain McClenaghan, Ian Jacobs, Ines Akrap, Ismael Velasco, Iulia Raluca Ionita, James Christie, Jeffrey Yasskin, Jennifer Strickland, Jens Oliver Meiert, Jeroen Hulscher, Jim McCool, Josh Kim, Julien Wilhelm, Kazuhito Kidachi, Kenneth G. Franqueiro, Laurent Devernay Satyagraha, Len Dierickx, Leon Brocard, Lewis Halstead, Łukasz Mastalerz, Marie Ototoi, Michelle Barker, Mike Gifford, Morgan Murrah, Nahuai Badiola, Neil Clark, Nick Doty, Nick Lewis, Nicola Bonotto, Nigel Megitt, Oliver Winks, Orie Steele, Owen Barton, Owen Rogers, Peter Krautzberger, Philippe Le Hégaret, Richard Ishida, Romuald Priol, Rose Newell, Rudolf Van Der Berg, Ryan Sholin, Sandy Dähnert, Sarah Zama, Sarven Capadisli, Shane Herath, Siddhesh Wagle, Simon Perdrisat, Simone Onofri, Sorca Duffy, Susannah Hill, Tantek Çelik, Tej Kalianda, Theresa O'Connor, Thibaud Colas, Thorsten Jonas, Tim Frick, Tzviya Siegman, Youen Chéné, Yuna Orsini, Zoe Lopez-Latorre.

C.2 Other active participants, or contributors to supporting resources

Aiste Rugeviciute, Alekh Gupta, Alicia Pritchett, Anthony Vallée-Dubois, Antoine Abélard, Asim Hussain, Bee Flaherty, Boris Schapira, Brian Sharpe, Carine Bournez, Christophe Clouzeau, Christos Bacharakis, Danielle Subject, Denis Didier, Edward Bender, Elise West, Florence Maurice, Gerry McGovern, Greg McDonald, Ignacio Rondini, Ivano Malavolta, James Cannings, James Gallagher, Jan Henckens, Jean Rigotti, Jon Gibbins, Juan Sotés, Julien Robitaille, Kate Mroczkowski, Katya Dreyer-Oren, Kimi Wei, Laila Tamani, Leah Goldfarb, Lenchi Danch, Loren Velasquez, Louise Towler, Luciene Bulhões Mattos, Luis Tiago, Manfred Jurgovsky, Marie Koesnodihardjo, Mark Butcher, Marketa Benisek, Mert Altinöz, Michelle Sanver, Moritz Guth, Nicholas Oliveira, Nick Oliveira, Nick Sollecito, Nicolas Lanthemann, Nicolas Oren, Patrick Hypscher, Pietro Jarre, Radu Micu, Rafael Lebre, Rebecca Brocton, Rick Butterfield, Rick Viscomi, Robin Whittleton, Samuel Pitoňák, Sandra Pallier, Sebastien Solere, Sylvain Tenier, Thierry Leboucq, Thomas Alexander Munch-Woolff, Tom Greenwood, Tom Howells, Torsten Beyer, Tristan Nitot, Yelle Lieder, Youcef Bekhti.

D. Changelog

Note that this changelog only identifies substantive changes since the final draft Community Group Report dated Dec 6, 2024.

For a list of all issues addressed, refer to the Interest Group and former Community Group issue trackers.

Ongoing Release Notes

Additions:

  • [#348] WSG Impact Measurement & Impact JSON API dataset launched.
    @anewmandev, @AlexDawsonUK, @andreadavanzo, @awright1979-alt, @mrchrisadams, @chrisn, @ehorrell, @fershad, @hanopcan, @hidde, @jyasskin, @jenstrickland, @ldevernay, @astuanax, @lmastalerz, @mgifford, @the-sustainabledev, @nicolabonotto, @ohuu, @ryansholin, @systemstree, @susannah-hill, @tantek, @thorstenjonas, @timfrick, @TzviyaSiegman

Updates:

  • Added links to consideration section to W3C mission for a11y, security, and privacy.
    @AlexDawsonUK
  • Summary supplement deprecated & removed as it's content merged into WSG introduction.
    @AlexDawsonUK
  • Peer Review, Plain English, Tone & other content updates to UX Section.
    @AlexDawsonUK, @andreadavanzo, @awright1979-alt, @bkardell, @ChristianHiBr, @CrystalPrestonWatson, @mylonelycomputer, @ehorrell, @fershad, @hidde, @ines-akrap, @JamesChristie-SustainableUX, @jyasskin, @jenstrickland, @JeroenHulscher, @kazuhito-kidachi, @mgifford, @airbr, @the-sustainabledev, @codewordcreative, @ryansholin, @Sarahz27, @systemstree, @hober, @timfrick, & @TzviyaSiegman
  • Peer Review, Plain English, Tone & other content updates to WebDev Section.
    @AlexDawsonUK, @awright1979-alt, @CrystalPrestonWatson, @fershad, @hidde, @jyasskin, @kazuhito-kidachi, @Lewish1998, @lmastalerz, @airbr, @codewordcreative, @Sarahz27, @csarven, @systemstree, @tkalianda, @hober, @thorstenjonas, @timfrick, & @TzviyaSiegman
  • Peer Review, Plain English, Tone & other content updates to Infrastructure Section.
    @AlexDawsonUK, @fershad, @hidde, @ines-akrap, @JamesChristie-SustainableUX, @jyasskin, @Lewish1998, @lmastalerz, @mgifford, @airbr, @codewordcreative, @ryansholin, @Sarahz27, @systemstree, @susannah-hill, @hober, & @TzviyaSiegman
  • Peer Review, Plain English, Tone & other content updates to Business Section.
    @AlexDawsonUK, Alisa Bonsignore, @ChristianHiBr, @Jaromil, @mylonelycomputer, @fershad, @hidde, @ines-akrap, @jenstrickland, @kazuhito-kidachi, @lmastalerz, @mgifford, @airbr, @the-sustainabledev, @codewordcreative, @simoneonofri, @systemstree, @hober, @timfrick, & @TzviyaSiegman
  • [#216] Quick Reference updated to be more accessible and print friendly with the PDF removed.
    @AlexDawsonUK & @jenstrickland
  • [#243] Plain English introduction boxes are now expanded by default to maximize visibility.
    @AlexDawsonUK, @codewordcreative & @TzviyaSiegman
  • [#291] Introduction has been updated with new material from IG members and summary document.
    @AlexDawsonUK, @AnneFaubry, @hidde, @mgifford, @Psychpsyo, @codewordcreative, @ryansholin, @timfrick, & @TzviyaSiegman
  • [#309] Updates to the considerations and tagging to align better with benefits.
    @AlexDawsonUK
  • [#342] "Sustainability metrics" split into "Provider selection" and "Efficient operation" SCs.
    @AlexDawsonUK, @fershad, & @codewordcreative

Fixes:

  • Aligned some of the language between documents for consistency.
    @AlexDawsonUK & @codewordcreative
  • Broken links and redirects have been resolved or removed.
    @AlexDawsonUK & @kantoche
  • Numerous issues raised by TAG have been addressed for the introduction and UX section.
    @AlexDawsonUK, @codewordcreative, @susannah-hill, and @TzviyaSiegman
  • [#213] Horizontal Review feedback for Accessibility has been included.
    @AlexDawsonUK, @goodwitch, @JamesChristie-SustainableUX, @jenstrickland, @codewordcreative, & @TzviyaSiegman
  • [#214] Horizontal Review feedback for Internationalization has been included.
    @aphillips, @AlexDawsonUK, @svgeesus, @r12a, & @codewordcreative
  • [#215] Horizontal Review feedback for Privacy has been included.
    @AlexDawsonUK, @gbshankar, @codewordcreative, &@TzviyaSiegman
  • [#216] GreenIT URLs have been updated to match the latest release.
    @AlexDawsonUK
  • [#216] Ensured other deliverable cross-references all point to the TR specification URL.
    @AlexDawsonUK
  • [#232] Additional references added to the laws & policies supplement.
    @AlexDawsonUK
  • [#232] Statistics in the at-a-glance supplement have been updated.
    @AlexDawsonUK
  • [#247] Change to the paragraph preceeding GRI information for clarity.
    @AlexDawsonUK & @ChristianHiBr
  • [#351] Cross-linking now automatically reveals a details elements contents.
    @AlexDawsonUK
  • [#351] Numbering replaced with friendly ID's and URLs for better maintainability.
    @AlexDawsonUK
  • [#353] Examples not in HTML, CSS, or JS now describe what format they are in.
    @airbr
Q4 2025 Release Notes (15th December 2025)

Additions:

  • [#192] Added an AI tag to the filter system for relevant content.
    @TzviyaSiegman

Updates:

  • [#97] & [#191] Updates to the introduction content and glossary definitions.
    @awright1979-alt, @hidde, @ines-akrap, @mgifford, @codewordcreative, @systemstree, @timfrick, & @TzviyaSiegman
  • [#192] Filter system is more visible within TOC and multiPage removed.
    @AlexDawsonUK, @kfranqueiro, @timfrick, & @TzviyaSiegman
  • [#192] TOC updates and query strings in URL update to reflect active filters.
    @AlexDawsonUK & @fershad
  • [#192] Intro clarifications provided RE standards references.
    @TzviyaSiegman
  • [#192] Update to relationships to include W3C WebML WG Ethical Principles spec.
    @TzviyaSiegman
  • [#194] Multiple updates to the Hosting section applied by Infrastructure Task Force.
    @AlexDawsonUK, @codewordcreative, @ryansholin & @susannah-hill, & @TzviyaSiegman
  • [#195] Benefits have moved into a dedicated supplement for further refining.
    @AlexDawsonUK, @codewordcreative, @fershad, @nigelmegitt
  • [#197] Additional useful resources have been included within the specification.
    @AlexDawsonUK
  • [#197] Multiple updates to the User Experience section applied by UX Task Force.
    @aphillips, @AlexDawsonUK, @awright1979-alt, @AnneFaubry, @ChrisButterworth, @fantasai, @ehorrell, @fershad, @hidde, @ines-akrap, @JamesChristie-SustainableUX, @jenstrickland, @kazuhito-kidachi, @mgifford, @airbr, @the-sustainabledev, @nigelmegitt, @r12a, @codewordcreative, @Sarahz27, @systemstree, @sorca11y, @thorstenjonas, & @TzviyaSiegman
  • [#197] Update to 5.20 to provide clarity around emerging technologies and AI.
    @AlexDawsonUK & @codewordcreative

Fixes:

  • [#25] Per IG consensus, testability bubbles have been removed until it can be assured.
    @fershad, @hidde, & @jyasskin
  • [#192] Additional fixes for pubRules prior to draft note status.
    @AlexDawsonUK, @plehegar, & @TzviyaSiegman
  • [#192] Fixed some redundancy issues within the specification.
    @AlexDawsonUK
  • [#192] Updated editor roles and credit for @codewordcreative Q3-2025 contributions.
    @AlexDawsonUK, @ines-akrap, @mgifford, @timfrick, & @TzviyaSiegman
  • [#197] Broken links and redirects have been resolved or removed.
    @AlexDawsonUK
  • [#197] Overlapping success criteria have been merged, grouped, or removed.
    @AlexDawsonUK, @chrisn, @fullo, @hidde, @jyasskin, @kazuhito-kidachi, @mgifford, @airbr, @codewordcreative, @systemstree, @timfrick, & @TzviyaSiegman
  • [#197] Supplements list in WSG header have improved label descriptions.
    @AlexDawsonUK
  • [#200] Minor fix applied to Organize code arrangement.
    @fershad
  • [#201] Update applied to STAR materials on Lazy Loading.
    @airbr & @tunetheweb
Q3 2025 Release Notes (15th September 2025)

Additions:

  • [#122] Added dark mode capability to the specification and supplements.
    @AlexDawsonUK

Updates:

  • [#116] & [#127] Editorial improvements have been provided for the introduction.
    @AlexDawsonUK, @AnneFaubry, @codewordcreative, @fershad, & @ldevernay
  • [#125] Obsolete impact and effort ratings have been removed from the spec.
    @AlexDawsonUK
  • [#128] Updated content for the Summary supplement (formerly Intro).
    @AlexDawsonUK & @AnneFaubry

Fixes:

  • [#70] & [#117] Global editorial improvements and bug fixes have been applied to WSG.
    @AlexDawsonUK, @codewordcreative, @jenstrickland, @mrchrisadams, & @ryansholin
  • [#79] & [#119] Intents have been updated, shortened, and turned into guideline subheadings.
    @airbr, @AlexDawsonUK, Alisa Bonsignore, @andreadavanzo, @codewordcreative, @Sarahz27, @susannah-hill & @TzviyaSiegman
  • [#89] & [#90] Structure of the crossover links has been improved for accessibility.
    @jenstrickland, @pkra, @TzviyaSiegman
  • [#90] Attribution for authors now conforms to pubRules with acknowledgements link.
    @AlexDawsonUK & @TzviyaSiegman
  • [#93], [#102], & [#104] Editorial improvements have been provided for the web dev success criteria.
    @airbr, @AlexDawsonUK, @codewordcreative, @fershad, @hidde, @ryansholin, & @TzviyaSiegman
  • [#100] Editorial improvements have been provided for the category introductions.
    @AlexDawsonUK, @awright1979-alt, @codewordcreative, @fershad, @hidde, @ines-akrap, @jenstrickland, @ryansholin, @susannah-hill, @timfrick, & @TzviyaSiegman
  • [#101] Editorial improvements have been provided for the UX success criteria.
    @AlexDawsonUK, @awright1979-alt, @ChrisButterworth, @codewordcreative, @fershad, @jenstrickland, @Sarahz27, @systemstree, @the-sustainabledev, @thorstenjonas, & @TzviyaSiegman
  • [#105] Editorial improvements have been provided for the hosting success criteria.
    @AlexDawsonUK, @codewordcreative, @fershad, @susannah-hill, @ryansholin, & @TzviyaSiegman
  • [#107] Editorial improvements have been provided for the business success criteria.
    @AlexDawsonUK, @codewordcreative, @fershad, @timfrick, & @TzviyaSiegman
  • [#108] Editorial improvements have been provided for the UX benefits.
    @awright1979-alt, @codewordcreative, @jenstrickland, @Sarahz27, @thorstenjonas, & @TzviyaSiegman
  • [#109] Editorial improvements have been provided for the web dev benefits.
    @codewordcreative, @ryansholin, & @TzviyaSiegman
  • [#110] Editorial improvements have been provided for the hosting benefits.
    @codewordcreative, @susannah-hill, @ryansholin, & @TzviyaSiegman
  • [#112] & [#118] Broken links and redirects have been resolved or removed.
    @AlexDawsonUK & @ldevernay
  • [#113] Editorial improvements have been provided for the business benefits.
    @codewordcreative, @timfrick, & @TzviyaSiegman
  • [#114], [#125], & [#132] Editorial improvements have been provided for the examples.
    @AlexDawsonUK, @codewordcreative, @the-sustainabledev, & @timfrick
  • [#118] & [#125] Broken links and redirects have been resolved or removed.
    @AlexDawsonUK
  • [#120] Resolved an issue around language use of normative in supporting documents.
    @frivoal, @hidde, @tantek
  • [#121] & [#122] Alignment with W3C Principle Notes, Manual of Style, and QA Framework.
    @AlexDawsonUK, @codewordcreative, & @hidde
  • [#122] Aligned all documents with mandatory pubRules requirements.
    @AlexDawsonUK
  • [#125] Fixed a minor bug related to the print style sheet.
    @AlexDawsonUK
Q2 2025 Release Notes (30th June 2025)

Additions:

  • [#6] New resources supplement that will serve as the repository for sustainability links.
    @AlexDawsonUK
  • [#14], [#58], [#67], & [#68] Guideline filters using data-attributes (for full-document mode) available.
    @airbr, @AlexDawsonUK, @ldevernay, @timfrick, & @TzviyaSiegman
  • [#41] Living changelog section has been added to WSG (Github releases will continue).
    @AlexDawsonUK & @TzviyaSiegman
  • [#53] New success criteria for 4.1 providing coverage regarding the impact of domain names.
    @codewordcreative & @exortech
  • [#68] New considerations section with accessibility, internationalization, privacy, and security cross-references.
    @AlexDawsonUK & @TzviyaSiegman

Updates:

  • [#30] & [#55] Former accessibility guideline 3.5 is removed. Useful material merged into SC for 2.29.
    @airbr, @andreadavanzo, & @hidde
  • [#45] Success criteria for 3.11 updated to reflect more appropriate structured data use.
    @hidde
  • [#51] Success criteria for 3.5 updated on to avoid CSS methodology naming.
    @airbr & @andreadavanzo
  • [#52] & [#67] Deliverables updated to ensure case-use and interactive elements are consistant.
    @AlexDawsonUK
  • [#56] Category intros have been re-written to include more material (subheadings, goals & benefits).
    @AlexDawsonUK & @codewordcreative
  • [#67] & [#72] Additional useful resources have been included within the specification.
    @AlexDawsonUK
  • [#67] Updated the introduction to provide better coverage of new sections and supplements.
    @AlexDawsonUK
  • [#67] Tags have been sorted into alphabetical order to maximize readability.
    @AlexDawsonUK

Fixes:

  • [#41] Fixed abbreviation usage to ensure alignment across the specification and deliverables.
    @AlexDawsonUK
  • [#41] Resolved some outdated website references that existed within the STAR test suite.
    @AlexDawsonUK
  • [#42] Fixed multiPage issues including left-padding on buttons and full-document refresh.
    @AlexDawsonUK
  • [#42] Glossary now correctly appears as part of the index rather than the main WSG document.
    @AlexDawsonUK
  • [#42], [#43], & [#48] Multiple spelling and grammar fixes have been applied to the document.
    @AlexDawsonUK & @hidde
  • [#50] Fixed the references to particular files by noting the full filename alongside.
    @airbr
  • [#59] & [#80] Broken links and redirects have been resolved or removed.
    @AlexDawsonUK
  • [#60] & [#68] Removed obsolete CSS and JavaScript in the source code to improve performance.
    @AlexDawsonUK
  • [#60] Updated some of the tags to reflect new and updated success criteria material.
    @AlexDawsonUK
  • [#67] Further global grammatical fixes have been applied to improve the content quality.
    @codewordcreative
  • [#67] Success criteria have accurate identifiers sans external resources like testability.
    @AlexDawsonUK
  • [#73] Fixed an issue that caused Firefox's in-page search to suffer multiPage issues.
    @TzviyaSiegman
  • [#80] Fixed an issue that caused searching in multi-page view to not work correctly.
    @dontcallmedom
  • [#82] Fixed a couple of rogue full-document in-page search issues that triggered filtering.
    @AlexDawsonUK
Q1 2025 Release Notes (31st March 2025)

Additions:

  • A Jekyll configuration is provided for easy-to-read versions of the IG and WSG readmes.
    @AlexDawsonUK
  • A ReSpec multiPage plug-in was created for W3C specifications, so WSG now has pagination.
    @AlexDawsonUK, @hidde, @kazuhito-kidachi, & @TzviyaSiegman
  • New IG readme, WSG readme, contributing & IE policy to reflect new W3C status.
    @AlexDawsonUK, @ines-akrap, @mgifford, @timfrick, & @TzviyaSiegman
  • New success criteria for 2.4 on sustainable brand development and asset management.
    @codewordcreative
  • New success criteria for 3.14 on Energy-relevant APIs that may be beneficial.
    @AlexDawsonUK
  • New success criteria for 5.22 on automated tooling covering scraping technology.
    @codewordcreative
  • STAR JSON API has been published with techniques and test suite URLs.
    @AlexDawsonUK & @mgifford
  • [#15] A New introduction section on relationships to other specifications (and bodies) is included.
    @AlexDawsonUK & @TzviyaSiegman
  • [#17] New success criteria for 4.9 on Data processing efficiency covering Redundant processing.
    @jyasskin

Updates:

  • Additional information sections were redesigned to increase interaction visibility.
    @AlexDawsonUK
  • Additional useful resources have been included within the specification.
    @AlexDawsonUK
  • Guideline titles have been expanded to be more explanatory of the actionable SCs.
    @AlexDawsonUK & @torgo
  • The Laws & Policies document has additional legislation with references and fixes included.
    @AlexDawsonUK
  • Success criteria for guideline 2.17 now includes mentions of animation iterations.
    @codewordcreative
  • Success criteria for guideline 4.9 now include improved protocol usage compatibility.
    @ldevernay & @mgifford
  • Update to guideline 4.2 to be more inclusive of both client and server-side.
    @ldevernay & @mgifford
  • WSG has been successfully transitioned from CG to W3C IG repository.
    @AlexDawsonUK
  • [#4] Update to guideline 2.16 SC among others to remove language ambiguity.
    @timfrick
  • [#14] Guideline descriptions relabeled as Intent and temporarily moved to additional information.
    @AlexDawsonUK
  • [#16] Former Guidelines 3.18-19 have been merged into a single Guideline.
    @andreadavanzo
  • [#20] & [#24] Update to guideline 3.7 SCs to improve the criteria robustness.
    @andreadavanzo & @hidde
  • [#21] Two success criteria for guideline 3.19 have been merged into a single SC.
    @andreadavanzo & @hidde
  • [#23] Two success criteria for guideline 5.20 have been merged.
    @andreadavanzo
  • [#27] Success criteria for guideline 3.2 now includes more detail about data types.
    @andreadavanzo
  • [#28] Success criteria for guideline 3.3 now includes modular front and back-end code.
    @andreadavanzo
  • [#32] Success criteria for guideline 3.7 are more extensively defined.
    @fullo, @hidde, & @kazuhito-kidachi
  • [#35] Success criteria for guideline 3.19 now includes avoiding polyfills in modern browsers.
    @AlexDawsonUK

Fixes:

  • Broken links and redirects have been resolved or removed.
    @AlexDawsonUK
  • Group Status changed from a CG Draft to a W3C Editors Draft.
    @AlexDawsonUK
  • Guideline headings are now in sentence case to improve readability.
    @AlexDawsonUK
  • Missing test suite references in the table have now been resolved.
    @AlexDawsonUK
  • References to SustyWeb changed to IG (and URLs updated to match).
    @AlexDawsonUK
  • Resolved some issues with citation conventions being incorrect.
    @AlexDawsonUK
  • SustyWeb Community links & specifications now have superseded notice.
    @AlexDawsonUK, @ianbjacobs, & @TzviyaSiegman
  • Versioning references removed to match living document status.
    @AlexDawsonUK
  • [#26] Resolved some issues with internal references to material being incorrect.
    @airbr
  • [#31] Multiple spelling and grammar fixes have been applied.
    @AlexDawsonUK, @codewordcreative, & @hidde

If you spot any new bugs, or have new content or ideas to include, submit an issue.

E. References

E.1 Informative references

[COMMS]
Between 2010 and 2021, global emissions from digital technologies were largely obscured in greenhouse gas emission accounting standards. Janna Axenbeck, Stefanie Kunkel, Joris Blain, and Francis Charpentier. 28 January 2026. Informational. URL: https://www.nature.com/articles/s44458-025-00022-6
[design-principles]
Web Platform Design Principles. Martin Thomson; Jeffrey Yasskin. W3C. 24 February 2026. W3C Working Group Note. URL: https://www.w3.org/TR/design-principles/
[ethical-web-principles]
Ethical Web Principles. Daniel Appelquist; Hadley Beeman; Amy Guy. W3C. 12 December 2024. STMT. URL: https://www.w3.org/TR/ethical-web-principles/
[fingerprinting-guidance]
Mitigating Browser Fingerprinting in Web Specifications. Nick Doty; Tom Ritter. W3C. 25 September 2025. W3C Working Group Note. URL: https://www.w3.org/TR/fingerprinting-guidance/
[GRI]
Global Reporting Initiative. Global Reporting Initiative. 30 June 2022. Informational. URL: https://www.globalreporting.org/
[HR-Spec]
Human rights and technical standard-setting for the Web. Nick Doty, Alissa Cooper, and Wendy Seltzer. 10 March 2023. Informational. URL: https://cdt.org/wp-content/uploads/2023/03/human-rights-web-standards.html
[ICT-IMPACT]
The real climate and transformative impact of ICT: A critique of estimates, trends, and regulations. Charlotte Freitag, Mike Berners-Lee, Kelly Widdicks, Bran Knowles, Gordon S. Blair, and Adrian Friday. 10 September 2021. Informational. URL: https://www.cell.com/patterns/pdfExtended/S2666-3899(21)00188-4
[MANIFESTO]
Sustainable Web Manifesto. Wholegrain Digital. Informational. URL: https://www.sustainablewebmanifesto.com/
[privacy-principles]
Privacy Principles. Robin Berjon; Jeffrey Yasskin. W3C. 15 May 2025. STMT. URL: https://www.w3.org/TR/privacy-principles/
[SHIFT]
Lean ICT: Towards digital sobriety. The Shift Project. 09 March 2019. Informational. URL: https://theshiftproject.org/en/publications/lean-ict/
[VARIABLES]
The Variables of Web Sustainability. Alexander Dawson. 22 January 2023. Informational. URL: https://websitesustainability.com/cache/files/variables.pdf
[WCAG]
Web Content Accessibility Guidelines (WCAG) 2.2. Michael Cooper; Andrew Kirkpatrick; Alastair Campbell; Rachael Bradley Montgomery; Charles Adams. W3C. 12 December 2024. W3C Recommendation. URL: https://www.w3.org/TR/WCAG22/
[webmachinelearning-ethics]
Ethical Principles for Web Machine Learning. Anssi Kostiainen. W3C. 8 January 2024. DNOTE. URL: https://www.w3.org/TR/webmachinelearning-ethics/