baseline-browser-mapping

By the W3C WebDX Community Group and contributors.

baseline-browser-mapping exposes arrays of browsers compatible with Baseline Widely Available and specified Baseline year feature sets. You can use baseline-browser-mapping to help you determine minimum browser version support for your chosen Baseline feature set.

Prerequisites

To use this package, you'll need:

• Node.js (a supported current, active LTS, or maintenance LTS release)

Install

To install the package, run:

npm install --save baseline-browser-mapping

baseline-browser-mapping depends on web-features and @mdn/browser-compat-data for version selection. It is strongly recommended that you update this module and it's dependencies often to ensure you have the most accurate data. Consider adding a script to your package.json and using it as a build step:

"scripts": [
  "refresh-baseline-browser-mapping": "npm i --save baseline-browser-mapping@latest web-features@latest @mdn/browser-compat-data@latest"
]

Usage

Get Baseline Widely Available browser versions

To get the current list of minimum browser versions compatible with Baseline Widely Available features from the core browser set, call the getCompatibleVersions() function with:

import { getCompatibleVersions } from "baseline-browser-mapping";

getCompatibleVersions();

Executed on 7th March 2025, the above code returns the following browser versions:

[
  { browser: "chrome", version: "105", release_date: "2022-09-02" },
  {
    browser: "chrome_android",
    version: "105",
    release_date: "2022-09-02",
  },
  { browser: "edge", version: "105", release_date: "2022-09-02" },
  { browser: "firefox", version: "104", release_date: "2022-08-23" },
  {
    browser: "firefox_android",
    version: "104",
    release_date: "2022-08-23",
  },
  { browser: "safari", version: "15.6", release_date: "2022-09-02" },
  {
    browser: "safari_ios",
    version: "15.6",
    release_date: "2022-09-02",
  },
];

[!NOTE]
The minimum versions of each browser are not strictly the final release before the Widely Available cutoff date of TODAY - 30 MONTHS. Some earlier versions will have supported the full Widely Available feature set.

Configuration options

getCompatibleVersions() accepts an Object as an argument with configuration options. The defaults are as follows:

{
  targetYear: undefined,
  widelyAvailableOnDate: undefined,
  includeDownstreamBrowsers: false,
  listAllCompatibleVersions: false
}

targetYear

The targetYear option returns the minimum browser versions compatible with all interoperable features at the end of the specific calendar year. For example, calling:

getCompatibleVersions({
  targetYear: 2020,
});

Returns the following versions:

[
  { browser: "chrome", version: "87", release_date: "2020-11-19" },
  {
    browser: "chrome_android",
    version: "87",
    release_date: "2020-11-19",
  },
  { browser: "edge", version: "87", release_date: "2020-11-19" },
  { browser: "firefox", version: "83", release_date: "2020-11-17" },
  {
    browser: "firefox_android",
    version: "83",
    release_date: "2020-11-17",
  },
  { browser: "safari", version: "14", release_date: "2020-09-16" },
  { browser: "safari_ios", version: "14", release_date: "2020-09-16" },
];

[!NOTE]
The minimum version of each browser is not necessarily the final version released in that calendar year. In the above example, Firefox 84 was the final version released in 2020; however Firefox 83 supported all of the features that were interoperable at the end of 2020.

[!WARNING]
You cannot use targetYear and widelyAavailableDate together. Please only use one of these options at a time.

widelyAvailableOnDate

The widelyAvailableOnDate options returns the minimum versions compatible with Baseline Widely Available on a specified date in the formay YYYY-MM-DD:

getCompatibleVersions({
  widelyAvailableOnDate: `2023-04-05`,
});

[!TIP]
This can be particularly useful if you provide a versioned library that target Baseline Widely Available on each version's release date and want to provide a table of minimum supported browsers in your documentation.

includeDownstreamBrowsers

Setting includeDownstreamBrowsers to true will include browsers outside of the Baseline core browser set where it is possible to map those browsers to an upstream Chromium version:

getCompatibleVersions({
  widelyAvailableOnDate: `2023-04-05`,
});

For more information on downstream browsers, see the section on downstream browsers below.

listAllCompatibleVersions

If you need a list of all compatible versions, pass an object with the listAllCompatibleVersions :

getCompatibleVersions({
  listAllCompatibleVersions: true,
});

Downstream browsers

Limitations

The browser versions in this module come from two different sources:

• MDN's browser-compat-data module.
• Parsed user agent strings provided by useragents.io

MDN browser-compat-data is an authoritative source of information for the browsers it contains. The release dates for the Baseline core browser set and the mapping of downstream browsers to Chromium versions should be considered accurate.

Browser mappings from useragents.io are provided on a best effort basis. They assume that browser vendors are accurately stating the Chromium version they have implemented. The initial set of version mappings was derived from a bulk export in November 2024. This version was iterated over with a Regex match looking for a major Chrome version and a corresponding version of the browser in question, e.g.:

Mozilla/5.0 (Linux; U; Android 10; en-US; STK-L21 Build/HUAWEISTK-L21) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/100.0.4896.58 UCBrowser/13.8.2.1324 Mobile Safari/537.36

Shows UC Browser Mobile 13.8 implementing Chromium 100, and:

Mozilla/5.0 (Linux; arm_64; Android 11; Redmi Note 8 Pro) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.6613.123 YaBrowser/24.10.2.123.00 SA/3 Mobile Safari/537.36

Shows Yandex Browser Mobile 24.10 implementing Chromium 128. The Chromium version from this string is mapped to the main Chrome version from MDN browser-compat-data.

[!NOTE]
Where possible, approximate release dates have been included based on useragents.io "first seen" data. useragents.io does not have "first seen" dates prior to June 2020. However, these browsers' Baseline compatibility is determined by their Chromium version, so their release dates are more informative than critical.

This data is updated on a daily basis using a script triggered by a GitHub action. Useragents.io provides a private API for this module which exposes the last 7 days of newly seen user agents for the currently tracked browsers. If a new major version of one of the tracked browsers is encountered with a Chromium version that meets or exceeds the previous latest version of that browser, it is added to the src/data/downstream-browsers.json file with the date it was first seen by useragents.io as its release date.

List of downstream browsers

[!NOTE]
All the non-core browsers currently included implement Chromium. Their inclusion in any of the above methods is based on the Baseline feature set supported by the Chromium version they implement, not their release date.

Helping out and getting help

baseline-browser-mapping is part of the W3C WebDX Community Group's web-features project. Go to web-platform-dx/web-features for more information on contributing or getting help.