mozilla/webextension-polyfill

Health v2 · maintenance only

Flags: archived

Adoption not part of the score

3069 stars · 238 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-29, confidence not recorded

A lightweight polyfill that lets browser extensions use the Promise-based `browser` API namespace in Chrome, matching Firefox's WebExtension API style. It is now a no-op on browsers with native support and the project has been retired since Chrome adopted the `browser` namespace.

Use cases

• write chrome extensions using promise-based browser APIs
• make a webextension codebase work across chrome and firefox
• avoid callback-style chrome.* APIs in extension code
• use the same extension API namespace in chrome, edge, and opera
• write cross-browser extensions with typescript support

When to choose

• maintaining an older extension that still targets Chrome versions before 148
• supporting legacy Chrome-based browsers (Edge <79, old Opera) that lack the browser namespace

When to avoid

• starting a new extension targeting modern Chrome (148+) or Firefox, which support the browser namespace natively
• needing a maintained library - the project explicitly will not receive further updates
• building extensions only for Firefox or Safari, where the polyfill is a no-op

Facets

library · maturity abandoned

sdk developer-tools browser-extensions web-development developer-tools browser browser-extension webextension polyfill promise-based-api browser-api chrome-extension cross-browser javascript

Member repositories

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markdown · JSON · MCP: product_card(name="mozilla/webextension-polyfill")