Autoprefixer is a PostCSS plugin and tool that parses CSS and adds vendor prefixes to CSS rules based on browser support data from Can I Use. It helps you write CSS without vendor prefixes and automatically generates the needed prefixed versions for targeted browsers.
Project status
- Actively maintained: Recent GitHub updates are frequent (last upstream push on 2026-09-04, with 10.5.5 on 2026-09-04), indicating the project is currently in active development rather than dormant.
- Updates cadence: The update pattern from 2026-01-30 to 2026-09-04 shows multiple incremental updates, with typical gaps of weeks to about two months (for example, 10.5.5 on 2026-09-04, then 10.5.4 on 2026-07-16).
AI summary generated
Recent updates
10.5.6
Release 10.5.6 updates autoprefixer’s gradient handling to avoid generating incorrect old WebKit (-webkit-gradient) syntax. The primary documented change is to fix old -webkit gradient output.
10.5.5
Release 10.5.5 focuses on improving the performance of parsing resolution-based media queries. The code change updates the resolution parsing regex, adds a regression test for very long queries to prevent hanging, and extends test fixtures for additional valid resolution formats.
10.5.4
Version 10.5.4 includes a targeted fix for duplicated prefixed selector rules. The code change improves how selector lists are compared, specifically handling cases where the selector list formatting differs (for example, different comma/newline formatting).
10.5.3
Release 10.5.3 contains a small fix focused on the brackets parser and the gradient parser. Code changes add defensive handling for edge-case input so parsing no longer throws on malformed bracket sequences or gradient arguments.
10.5.2
Autoprefixer 10.5.2 changes how it orders intrinsic stretch-related width fallbacks by reordering the generated vendor values. The release notes claim one ordering change, but the actual code and updated test/README outputs show the opposite ordering for Firefox-related values.
Breaking10.5.1
Release 10.5.1 fixes an issue where grid-area MSIE span values were not reset correctly when a later rule overrides a broader grid area. The code change also adds more robust selector overlap detection to decide when the row and column spans should be adjusted.
10.5.0
Version 10.5.0 primarily adds vendor prefix support for the CSS mask-position-x and mask-position-y properties. The diff also includes build and developer tooling changes (lint/test tooling), plus updates to runtime data dependencies that can change prefixing behavior beyond the single documented feature.
Features10.4.27
Release 10.4.27 primarily updates project metadata and publishing-related tooling. The release notes claim only a removal of the development key from package.json, while the actual diff also shows a dependency version bump for clean-publish.
10.4.26
Release 10.4.26 claims only one change: reduced package size. The diff shows this was implemented via publishing configuration changes, plus updates to dev tooling dependencies and their lockfile resolution.
10.4.25
Version 10.4.25 includes a fix for gradient handling when CSS Custom Properties (CSS variables) are used, specifically addressing broken output in legacy gradient generation. The code changes add a guard to avoid generating the older WebKit gradient form when a gradient value contains var(...).
10.4.24
Release 10.4.24 updates the project version and claims a small Autoprefixer performance improvement. The code diff shows micro-optimizations (replacing Array.concat patterns with push/push spread) plus a patch bump of caniuse-lite used for prefix data.
10.4.23
Release 10.4.23 makes a small dependency cleanup and updates various tooling dependencies and CI actions. While the release notes only mention dependency reduction, the code diff also changes how gradient angle values are normalized.
10.4.22
Release 10.4.22 primarily updates how Autoprefixer determines prefixes for `width: stretch` based on newer Can I Use data. It also bumps `fraction.js` to a newer major version and refreshes dependency metadata used during prefixing.
10.4.21
Release 10.4.21 focuses on correcting how Autoprefixer generates the selector for `:placeholder-shown` when the `-moz-` prefix is involved. The code diff also includes dependency bumps and some internal import reordering, but no other user-facing logic changes are evident from the provided diff.
10.4.20
Release 10.4.20 primarily adjusts autoprefixer’s handling of the `fit-content` prefixing behavior specifically for Firefox. In addition to the documented Firefox fix, the diff shows dependency and tooling updates that can indirectly change prefixing outcomes across other CSS features.
10.4.19
Release 10.4.19 removes the mixed-support warning logic related to using `start` and `end` on flex alignment/justification properties. The code change also eliminates the associated test coverage for those warnings, and updates several tooling and dependency versions (including `caniuse-lite`).