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MDN data

Maintained by the MDN team at Mozilla.

This repository contains general data for Web technologies.

This data is used in MDN documentation, to build information boxes or sidebar navigation. External tools have started to make use of this data as well. For example, the CSSTree CSS parser.

NPM version lint

Repository contents

There's a top-level directory for each broad area covered: for example, api and css. Inside each of these directories is one or more JSON files containing the data.


Contains data about Web APIs:

  • API inheritance (interface inheritance and mixin implementations)


Contains data about:

  • CSS at-rules
  • CSS properties
  • CSS selectors
  • CSS syntaxes
  • CSS types
  • CSS units

Read more about CSS data and the format of the files.


The l10n folder contains localization strings that are used in the various json files throughout this repository.


If you find a problem, please file an issue.


We're very happy to accept contributions to this data. Please familiarize yourself with the schema for the data you're editing, and send us a pull request. See also the Contributing file for more information.

See also