Tailwind CSS v4 is a ground-up rewrite with a new engine called Oxide. Here's what changed.
CSS-First Configuration
No more tailwind.config.js. Configure everything in CSS using @theme directives.
Automatic Content Detection
Tailwind v4 automatically finds your template files. No more configuring content paths.
Performance
The new Oxide engine is up to 10x faster for full builds and 100x faster for incremental builds.
New Features
Migration
The official migration tool handles most changes automatically. Manual fixes are needed for custom plugins.