postcss/autoprefixer

Autoprefixer is a PostCSS plugin that automatically adds vendor prefixes to CSS properties based on current browser compatibility data. It processes stylesheets to ensure support for legacy browsers by applying specific hacks for features like Flexbox, Grid, and modern CSS values. The system operates via a CLI or build tool integration, relying on the caniuse-lite library to determine which prefixes are necessary for the target browser set.

A new executable script \bin/autoprefixer\ is introduced, allowing users to run Autoprefixer from the command line. It supports the \--info\ flag to display target browsers and used prefixes, \--version\ to show the current version number, and \--help\ for usage instructions.

bin · high confidence

The \lib/hacks\ directory now includes dedicated modules for a wide range of CSS properties, significantly broadening autoprefixer coverage. Flexbox support is extended with hacks for \align-content\, \align-items\, \align-self\, \flex-basis\, \flex-direction\, \flex-flow\, \flex-grow\, \flex-shrink\, \flex-wrap\, and \order\, handling legacy 2009 and 2012 spec variations. Grid layout support is substantially added with handlers for \grid-area\, \grid-column\, \grid-row\, \grid-template\, \grid-template-areas\, and related alignment and span properties, specifically targeting IE's \-ms-\ prefix requirements. Additional hacks cover \background-clip\, \background-size\, \border-image\, \border-radius\, \break-props\, \cross-fade\, \display-grid\, \filter\, \fullscreen\, \gradient\, \image-rendering\, \image-set\, \intrinsic\ sizing values, \mask-border\, \mask-composite\, \overscroll-behavior\, and pseudo-elements like \::file-selector-button\ and \:autofill\.

lib/hacks · high confidence

The project has been renamed from Rework Vendors to Autoprefixer and migrated from the Rework framework to PostCSS. This change updates the entry point to use the PostCSS API, allowing users to integrate the tool with modern build systems like Webpack, Gulp, and CLI workflows using PostCSS. The license has also been updated from LGPL to MIT.

(repo-wide) · high confidence

The internal data files for browser support and properties (browsers.js, props.js) have been removed and replaced with a new prefixes.js module that dynamically fetches prefixing rules from the caniuse-lite library. This change shifts the source of truth for CSS feature support from static, manually maintained JSON files to an external, up-to-date dependency, ensuring that prefixing decisions for properties like border-radius, animations, and gradients are driven by current browser compatibility statistics.

data · high confidence

The library has been rewritten in JavaScript to support PostCSS 8, introducing a new modular architecture with dedicated classes for handling at-rules, declarations, selectors, and values. This update brings improved performance through caching and reduced array allocations, adds support for modern CSS features like Grid Layout (with auto-placement and subgrid warnings), text-decoration-skip-ink, overscroll-behavior, and backdrop-filter, and deprecates the old \browsers\ option in favor of \overrideBrowserslist\. The \info()\ function now provides detailed output about selected browsers and required prefixes, and the plugin now uses \OnceExit\ for cleaner lifecycle management.

lib · high confidence

Added test cases for browserslist configuration and CSS output; Expanded test coverage for CSS Grid, Flexbox, and modern CSS features; Migrate test suite from CoffeeScript/Mocha to JavaScript/uvu; Removed outdated CSS prefix test output.

This release updates the project to version 10.6.1 and introduces a new pnpm lockfile (pnpm-lock.yaml) to manage dependencies. The package.json has been updated to reflect the new dependency tree, including runtime dependencies like browserslist (^4.28.9), caniuse-lite (^1.0.30001810), fraction.js (^5.3.4), picocolors (^1.1.1), and postcss-value-parser (^4.2.0). Development dependencies have also been updated to use oxlint (^1.83.0) for linting, uvu (^0.5.6) for testing, c8 (^12.0.0) for coverage, and postcss (^8.5.28). The funding information has been expanded to include OpenCollective, Tidelift, and GitHub Sponsors.

(dependencies) · high confidence

Written by watchdog.canine.dev from the codebase's own history, inside the signed delivery this page is composed from.

• CAI 58 → 54 (-3.9)
• Rubric changed (rubric-2026.09.11 → rubric-2026.09.18) — scores are not directly comparable.

• Code Health 49 → 49 (-0.2)
• Architecture 78 → 80 (+2.3)
• Maturity 60 → 60 (+0.2)
• Readiness 63 → 47 (-15.8)
• Security 80 → 86 (+5.6)

• Hotspot: lib/hacks/grid-utils.js (lib/hacks/grid-utils.js)

• High CVE: [GHSA redacted] (pnpm-lock.yaml)
• No direct assertions: checks mixed-case selectors repeatedly without matching quoted text (test/selector.test.js)
• No direct assertions: prefixes every matching selector regardless of case (test/autoprefixer.test.js)
• No direct assertions: prefixes mixed-case pseudo-classes without changing selector case (test/autoprefixer.test.js)
• No direct assertions: prefixes uppercase pseudo-elements (test/autoprefixer.test.js)
• Outdated (npm): caniuse-lite
• info.default (cognitive 38) (lib/info.js)
• info.default (cyclomatic 28) (lib/info.js)

• 1 commits — 0 feature/other, 1 fixes

• lib/selector.js — 1 commit

• fix: Fix case-insensitive pseudo-selector prefixing (#1558)

Written by watchdog.canine.dev from the codebase's own history, inside the signed delivery this page is composed from.

postcss/autoprefixer was measured the same way every project in this corpus was: the same rubric, at a pinned commit, with the result published in full. Point a surveyor at a repository you know and see whether you agree with it.