UnoCSS · Index

UnoCSS

On-demand atomic CSS engine with swappable presets, ~6kb, no core utilities

Tier S · Best in classToolGeneratorunocss.dev

UnoCSS is an atomic CSS engine by Anthony Fu that generates utilities on demand with no parsing, AST or file scanning. It ships no core utilities at all — everything comes from presets, so preset-wind3 and preset-wind4 reproduce Tailwind v3 and v4 syntax while preset-icons turns any Iconify icon into a pure-CSS class and preset-attributify moves utilities into HTML attributes. Integrations exist for Vite, Webpack, PostCSS, Nuxt, Astro, Svelte, Next.js and a CDN runtime, plus VS Code, JetBrains and Zed extensions. It is for teams that want Tailwind-shaped ergonomics with their own rule set and faster builds.

Install

npm install -D unocss

For an agent

Reach for UnoCSS over Tailwind when the project needs custom utility rules, attributify markup, or pure-CSS Iconify icons without a component wrapper — preset-icons alone (i-lucide-check as a class) removes a whole icon dependency. Pin the preset explicitly: preset-wind3 is Tailwind v3 syntax and preset-wind4 is v4, and copy-pasted Tailwind snippets silently miss utilities under the wrong one. Do not assume Tailwind plugins or shadcn/ui registries work here; most shadcn components assume real Tailwind and need the wind preset plus manual checking.

Why it is here. The strongest non-Tailwind atomic CSS engine, and the only one where the utility vocabulary itself is a swappable, authorable input.

Install command, framework, licence and component list.

Facts

License: MIT
Pricing: Free, Open source, Sponsor or ad supported
Framework: Vue, Nuxt, Svelte, Astro, Next.js, React, Vanilla JS
Styling: UnoCSS, Tailwind CSS, CSS custom properties
Distribution: npm package, CLI installer, GitHub repository
Platform: Web
Content type: Code
Agent readiness: Structured documentation, Readable open source, CLI installable
Accessibility: Not applicable
Maturity: Actively maintained
GitHub stars: 18,900
Package: unocss

Notable for

no core utilities — presets only
preset-icons: any Iconify icon as pure CSS
attributify and tagify modes
~6kb min+brotli, zero deps
v66.x, MIT, 18.9k stars

Provenance

Verified 2026-08-15. HTTP 200. https://unocss.dev/, https://unocss.dev/presets/ (full official preset list), https://github.com/unocss/unocss

Also in Utilities & Naming

unocss.devTier S