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  1. ab53fc3 Patch release containing data or non-breaking updates only by Florian Scholz · 2 weeks ago master v1.0.27
  2. 1efde7e Add Safari Web Extensions documentation (#6320) by Florian Scholz · 2 weeks ago
  3. b379453 Firefox 78esr ships Service Worker and Push (#6309) by Florian Scholz · 2 weeks ago
  4. 42260b8 Rename the "Slotable" mixin to "Slottable" (#6319) by Michael[tm] Smith · 2 weeks ago
  5. 9f7eb40 Add note about AddSearchProvider() becoming a no-op (#6311) by wbamberg · 3 weeks ago


This repository contains compatibility data for Web technologies. Browser compatibility data describes which platforms (where “platforms” are usually, but not always, web browsers) support particular Web APIs.

This data can be used in documentation, to build compatibility tables listing browser support for APIs. For example: Browser support for WebExtension APIs.

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You can install mdn-browser-compat-data as a node package.

npm install mdn-browser-compat-data


const bcd = require('mdn-browser-compat-data');;
// returns a compat data object (see schema)

Repository contents

There's a top-level directory for each broad area covered: for example, “http”, “javascript”, “webextensions”. Inside each of these directories is one or more JSON file containing the compatibility data.

  • api/ contains data for each Web API interface.

  • css/ contains data for CSS properties, selectors, and at-rules.

  • html/ contains data for HTML elements, attributes, and global attributes.

  • http/ contains data for HTTP headers, statuses, and methods.

  • javascript/ contains data for JavaScript built-in Objects, statement, operators, and other ECMAScript language features.

  • mathml/ contains data for MathML elements, attributes, and global attributes.

  • svg/ contains data for SVG elements, attributes, and global attributes.

  • webdriver/ contains data for WebDriver commands.

  • webextensions/ contains data for WebExtensions JavaScript APIs and manifest keys.

  • xpath/ contains data for XPath axes, and functions.

  • xslt/ contains data for XSLT elements, attributes, and global attributes.

Format of the browser compat json files

The definitive description of the format used to represent compatibility data is the schema file. You can also have a look at the schema documentation.


If you find a problem, please file a bug.


We're very happy to accept contributions to this data. See Contributing to browser-compat-data for more information.

Projects using the data

Here are some projects using the data, as an npm module or directly:

  • Add-ons Linter - the Add-ons Linter is used on and the web-ext tool. It uses browser-compat-data to check that the Firefox version that the add-on lists support for does in fact support the APIs used by the add-on.
  • Browser Compatibility Data Explorer - View, search, and visualize data from the compatibility dataset.
  • caniuse - In addition to the existing caniuse database, caniuse includes features from the MDN BCD project, formatted and interactive like any other caniuse support table.
  • Compat Report - Firefox Add-on that shows compatibility data for the current site in the developer tools.
  • compat-tester - Scan local documents for compatibility issues.
  • Visual Studio Code - Shows the compatibility information in the code completion popup.
  • - Hints to check if your CSS HTML and JavaScript have deprecated or not broadly supported features.
  • WebStorm - JavaScript IDE allowing you to check whether all CSS properties you use are supported in the target browser version.