# LeaVerou/prefixfree

Break free from CSS prefix hell!

Repository: https://github.com/LeaVerou/prefixfree
Canonical: https://ross.abutalabs.com/products/prefixfree
Homepage: http://projects.verou.me/prefixfree/
Language: JavaScript
License: MIT
License Family: permissive
Archived: true
Last push: 2021-10-13T20:37:47+00:00

## Health v2 (maintenance only)
Score: 10/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 35, longevity 100
- inputs: {"age_days": 5440, "days_push": 1785, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases, archived
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 3785, forks 698 (observed 2026-08-28T04:08:18.567173+00:00)

## What it is
-prefix-free is a small (2KB gzipped) JavaScript library that lets developers write unprefixed CSS3 properties and automatically adds the current browser's vendor prefix at runtime, only when needed. It processes stylesheets, style elements, and style attributes behind the scenes and exposes StyleFix and PrefixFree APIs for plugin authors.

## Use cases
- write unprefixed CSS3 properties without vendor prefixes
- automatically add -webkit- or -moz- prefixes at runtime
- support legacy browsers needing vendor prefixes for CSS3 features
- process inline style attributes for prefixing
- build custom CSS fixers with the StyleFix framework

## When to choose
- maintaining legacy sites targeting older browsers (IE9+, Firefox 3.5+) that require vendor prefixes
- you want to author clean, unprefixed CSS without a build step

## When to avoid
- modern projects targeting evergreen browsers where vendor prefixes are largely obsolete
- you prefer build-time autoprefixing tools like Autoprefixer over runtime processing
- you rely on @import-ed or cross-origin stylesheets, which are unsupported

## Facets
- artifact type: library
- maturity: maintenance
- function: css-framework, developer-tools
- domain: web-development, frontend
- platform: browser
- tags: css-vendor-prefixes, browser-compatibility, runtime-css-processing, javascript, web-server

## Member repositories
- LeaVerou/prefixfree (main) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:18.567173+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T18:27:41.259600+00:00, confidence not recorded.
  - readme: https://github.com/LeaVerou/prefixfree (fetched 2026-08-28T04:08:18.567173+00:00, sha 51e22a09d90e)
  - homepage: http://projects.verou.me/prefixfree/ (fetched 2026-08-29T09:22:22.438902+00:00, sha 3adfc9c8a339)
  - registry_npm: https://registry.npmjs.org/prefixfree (fetched 2026-08-29T09:22:22.441727+00:00, sha 1368ea451222)
- Data as of 2026-08-30T08:39:29.467469+00:00.