PostCSS CSS Transformer

PostCSS is a tool for transforming CSS with JavaScript plugins, providing a modular ecosystem that enables developers to use future CSS features today, automatically prefix properties, lint stylesheets, and enforce code conventions. At its core, it parses CSS into an abstract syntax tree that plugins can inspect and modify programmatically, then serializes the modified tree back into optimized CSS. The most widely used plugin, Autoprefixer, automatically adds vendor prefixes based on real browser usage data, eliminating the need to manually write browser-specific declarations. The Preset Env plugin enables developers to write modern CSS using upcoming standards and automatically polyfills features based on configurable browser targets. CSS Modules integration generates scoped class names, preventing style collisions between components in large applications. Stylelint integration enforces consistent conventions and catches errors during development, supporting standard CSS as well as extended syntaxes like SCSS. The plugin architecture supports over two hundred community plugins for tasks including minification, nesting, custom property transpilation, color function conversion, and grid layout fallbacks. The tool integrates with all major build systems including Webpack, Vite, Rollup, Parcel, and Gulp, and is used by industry leaders including Facebook, GitHub, Google, WordPress, and Wikipedia. Its extensible design and vibrant community make it a foundational layer in the modern CSS toolchain, powering frameworks like Tailwind CSS under the hood.