Sass

Tailwind CSS

tailwindlabs/tailwindcss

Popular

Utility-first CSS framework and today's dominant styling approach; v4 is CSS-first with a Rust engine.

PostCSS

postcss/postcss

Popular

Plugin-based CSS transformer behind autoprefixing and many frameworks' build pipelines.

CSS Modules

css-modules/css-modules

Locally scoped CSS class names by default; built into Vite, Next.js and most bundlers with zero runtime.

Lightning CSS

parcel-bundler/lightningcss

Rust-based CSS parser, transformer and minifier used by Vite and Tailwind CSS v4.

styled-components

styled-components/styled-components

Legacy

Runtime CSS-in-JS with tagged template literals; in maintenance mode and a poor fit for Server Components.

Emotion

emotion-js/emotion

Legacy

Runtime CSS-in-JS library used by older MUI versions; declining as zero-runtime styling takes over.

UnoCSS

unocss/unocss

Instant on-demand atomic CSS engine with presets compatible with Tailwind and Windi.

Panda CSS

chakra-ui/panda

Zero-runtime, type-safe CSS-in-JS with design tokens and recipes, from the Chakra UI team.

vanilla-extract

vanilla-extract-css/vanilla-extract

Zero-runtime stylesheets written in TypeScript with type-safe themes and variants.