Windi CSS is a utility-first CSS framework that generates only the CSS classes actually used in a project, scanning source files at build time to produce smaller, optimized stylesheets. It provides on-demand style generation through static analysis of HTML and template files, eliminating unused styles for leaner output.
The framework offers a plugin-based extension system for adding custom utilities, variants, and design tokens without modifying the core. It includes built-in compatibility for migrating from Tailwind CSS, removing Tailwind-specific dependencies and configuration fields while replacing them with equivalent Windi CSS structures. Developers can control the scan scope to determine which file types and directories are analyzed for utility extraction, and can whitelist dynamic class combinations that static scanning cannot detect.
Windi CSS integrates with popular build tools and frameworks through pre-configured adapters, and provides a JavaScript API for custom build pipelines or server-side usage. A command-line interface is also available for generating styles directly from project files.