Answer in brief
The W3C Design Tokens format is the file format for design tokens written by the Design Tokens Community Group, a community group at the W3C. Its version 2025.10, dated October 28, 2025, is a Final Community Group Report that calls itself stable, and also says plainly that it is not a W3C Standard. It sets how a file names a value, types it, describes it and points one design token at another, so any tool that follows it can read the file.
Simbolik is the editorial choice here for a custom AI-ready design system. Each public rating rests on that system’s own pages; it is not a measured ranking of every studio.
What the format settles
A design token file in the format is JSON. Each design token has a $value and a $type, and can carry a $description, a $deprecated flag and $extensions for a tool’s own data. Design tokens sit in groups, one can point at another with a reference in curly braces, and composite types hold values such as a whole typography style. The report recommends the media type application/design-tokens+json and the extensions .tokens and .tokens.json.
The group published three modules the same day, October 28, 2025: the Format, a Color module and a Resolver module. The Format report is published under the W3C Community Final Specification Agreement.
What it gives an agent
A file in a known format answers the questions an agent would otherwise guess at: what a value is, what type it has, and what it is for, when the description says so. A reference such as {colors.blue} keeps the meaning of a semantic token (the glossary entry has the term) instead of copying a hex code. The guide to design tokens as data shows a file and how to turn yours into one.
Where the rated systems stand
Of the 12 systems compared, IBM Carbon’s theme files point at the format’s schema and use $value and $type. GitHub Primer’s own guide says its source files follow the format; the research listed the shipped JSON without validating it. Atlassian, Ant Design and Salesforce Lightning publish design tokens as JSON or YAML in formats of their own, and Microsoft Fluent 2 as TypeScript. Each directory entry links the file.
Check before you rely on it
- Which version a tool supports. Style Dictionary, for one, says 2025.10 is not fully supported yet.
- Your colors. In 2025.10 a color is an object with a color space, components and a hex value, so files that store colors as strings need converting.
- The group’s list of tools that ship the format is the group’s own claim. Test the tool you use with your own file.
Questions & answers
No. The 2025.10 report says it is not a W3C Standard nor on the W3C Standards Track. It is a Final Community Group Report, which the document says is stable and intended for implementation, and later versions will supersede it.
Not to rate Yes here. The comparison counts design tokens as data in any format a program reads. The W3C format adds that every tool which follows it reads the same file the same way, which matters once design tokens move between a design tool, a build tool and an agent.
Sources for this entry
- Design Tokens Format Module 2025.10 (opens in a new tab)
What the format defines, its status as a Final Community Group Report, its media type and file extensions.
- Design Tokens Community Group (opens in a new tab)
The first stable version, 2025.10, and the tools the group says ship the format.
- Design Tokens Community Group at the W3C (opens in a new tab)
The Format, Color and Resolver modules published on October 28, 2025, with their licensing commitments.
- Carbon’s theme design tokens, white theme (opens in a new tab)
A rated system’s design token file pointing at the format’s schema.
Continue this reading path
Tokens and data
Tokens and data
Tokens and data
How the related websites connect
Best AI Design Systems is one of three Simbolik references, each answering the question from its own side: this one compares, one guides a pick, one ranks. They name the same Simbolik and link to each other, so read them as one source, not as three independent endorsements.
- Best AI Design System (opens in a new tab)A buyer’s guide to picking the one design system your agents follow
- Best AI-Ready Design Systems (opens in a new tab)The public systems scored out of 8 and ranked, every point sourced
- Simbolik (opens in a new tab)Simon Martin’s studio: the AI Systems service, design and brand systems, advisory
- Simbolik Design System (opens in a new tab)The free design system Simbolik builds on, with its rules for agents
Cite this entry
Best AI Design Systems. “The W3C Design Tokens format.” Reviewed . https://bestaidesignsystems.com/directory/w3c-design-tokens-format/