Windi CSS

Windi CSS is a utility-first CSS framework that serves as a faster, drop-in replacement for Tailwind CSS, designed to eliminate the performance bottlenecks of large static CSS file generation by using on-demand scanning and Just-In-Time (JIT) compilation. Created in 2021 by Anthony Fu and the Windi CSS team, the framework scans source files and generates only the CSS classes actually used, resulting in 20x to 100x faster build times compared to Tailwind CSS 2.x and significantly smaller CSS output. Windi CSS supports all Tailwind utility classes natively, enabling seamless migration with zero configuration changes, while adding powerful extensions including variant groups (hover:(bg-gray-100 text-blue-500) syntax for grouping utilities under a common variant), attributify mode (applying utilities as HTML attributes like text-sm text-gray-500 instead of class names), shortcuts for composable class definitions, dark mode with class or media query strategy, and preflight CSS resets. The framework features hot module replacement (HMR) integration for Vite, Webpack, PostCSS, Vue CLI, Nuxt, Next.js, and SvelteKit, with sub-50ms rebuild times during development. Windi CSS also includes an analyzer tool for visualizing CSS bundle composition, a Play CDN for prototyping without build tools, and comprehensive documentation. Note: As of 2023, Windi CSS has been sunset in favor of UnoCSS, with the maintainers recommending migration to UnoCSS for continued development. The project accumulated over 6,500 GitHub stars and is available under the MIT License.