A blazingly fast, utility-first CSS framework built with Bun. Crosswind generates only the CSS you need by scanning your files for utility classes, providing Tailwind CSS-compatible utilities with exceptional performance.
- ⚡️ Blazingly Fast - Built with Bun for exceptional performance (1000+ utilities in <10ms)
- 🎯 On-Demand Generation - Only generates CSS for utilities you actually use
- 🎨 Tailwind-Compatible - Familiar utility classes and syntax
- 💪 Fully Typed - Complete TypeScript support with type-safe configuration
- 🔧 Highly Configurable - Customize theme, colors, spacing, variants, and more
- 📦 Zero Runtime Dependencies - Minimal footprint, maximum performance
- 🔥 Hot Reload - Watch mode for instant rebuilds during development
- 🎭 Variant Support - Responsive, state (hover, focus, etc.), dark mode, and custom variants
- ✨ Modern CSS Features - Grid, Flexbox, animations, transforms, filters, and more
- 🔨 Class Compilation - Optimize HTML by compiling utility groups into single class names
- 🧪 Thoroughly Tested - 1300+ tests including comprehensive performance benchmarks
- 🚀 Production Ready - Minification, preflight CSS, and optimized builds
- ⌨️ CLI & API - Use via command line or programmatic API
bun add crosswind
# or
npm install crosswind- Initialize Crosswind:
# Create a config file
bunx crosswind initThis creates a crosswind.config.ts file:
import type { CrosswindOptions } from 'crosswind'
export default {
content: ['./src/**/*.{html,js,ts,jsx,tsx}'],
output: './dist/crosswind.css',
minify: false,
} satisfies CrosswindOptions- Add utility classes to your HTML:
<div class="flex items-center justify-between p-4 bg-blue-500 text-white rounded-lg shadow-md hover:bg-blue-600">
<h1 class="text-2xl font-bold">Hello Crosswind!</h1>
</div>- Build your CSS:
# Build once
bunx crosswind build
# Build and watch for changes
bunx crosswind watch
# Build with options
bunx crosswind build --output ./dist/styles.css --minifyYou can also use Crosswind programmatically:
import { build } from 'crosswind'
const result = await build({
content: ['./src/**/*.html'],
output: './dist/styles.css',
minify: true,
})
console.log(`Generated ${result.classes.size} classes in ${result.duration}ms`)Crosswind provides a comprehensive CLI:
crosswind build # Build CSS once
crosswind watch # Build and watch for changes
crosswind init # Create config file
crosswind analyze # Analyze utility class usage
crosswind clean # Remove output CSS file
crosswind preflight # Generate preflight CSS only
crosswind --version # Show version
crosswind --help # Show helpCrosswind supports extensive configuration options:
import type { CrosswindOptions } from 'crosswind'
export default {
// Content sources to scan for utility classes
content: ['./src/**/*.{html,js,ts,jsx,tsx}'],
// Output CSS file path
output: './dist/styles.css',
// Minify output CSS
minify: false,
// Enable watch mode
watch: false,
// Enable verbose logging
verbose: false,
// Theme customization
theme: {
colors: {
primary: '#3b82f6',
secondary: '#10b981',
// ... extend or override default colors
},
spacing: {
// ... customize spacing scale
},
fontSize: {
// ... customize font sizes
},
// ... and more
},
// Shortcuts (utility aliases)
shortcuts: {
btn: 'px-4 py-2 rounded bg-blue-500 text-white hover:bg-blue-600',
card: 'p-6 bg-white rounded-lg shadow-md',
},
// Custom variants
variants: {
// ... configure breakpoints, states, etc.
},
// Safelist (always include these classes)
safelist: ['bg-red-500', 'text-green-500'],
// Blocklist (never include these classes)
blocklist: ['debug-*'],
// Custom rules
rules: [],
// Preflight CSS (normalize/reset styles)
preflights: [],
// Presets
presets: [],
} satisfies CrosswindOptionsFor more configuration options, see the Configuration Guide.
Crosswind provides a comprehensive set of utility classes compatible with Tailwind CSS:
- Layout: display, position, overflow, z-index, etc.
- Flexbox & Grid: flex, grid, gap, align, justify, etc.
- Spacing: margin, padding with full scale support
- Sizing: width, height, min/max sizes
- Typography: font family, size, weight, line height, text alignment, etc.
- Backgrounds: colors, gradients, images, position, size
- Borders: width, color, radius, style
- Effects: shadow, opacity, blend modes, filters
- Transforms: translate, rotate, scale, skew
- Transitions & Animations: duration, timing, delay
- Interactivity: cursor, pointer events, user select, scroll behavior
- Advanced: mask utilities, backdrop filters, ring utilities
- Responsive:
sm:,md:,lg:,xl:,2xl: - State:
hover:,focus:,active:,disabled:,visited:,checked: - Pseudo-elements:
before:,after:,placeholder:,selection: - Group/Peer:
group-hover:,peer-focus: - Dark mode:
dark: - Positional:
first:,last:,odd:,even: - Important:
!prefix (e.g.,!text-red-500)
Crosswind supports arbitrary values for maximum flexibility:
<div class="w-[500px] h-[calc(100vh-4rem)] bg-[#1da1f2] text-[clamp(1rem,5vw,3rem)]">
Custom values!
</div>Optimize your HTML by compiling utility groups into single class names:
<!-- Before -->
<div class=":hw: flex items-center justify-between px-4 py-2 bg-white rounded-lg shadow-md">
Content
</div>
<!-- After build -->
<div class="hw-2k9d3a">
Content
</div>This reduces HTML file size by up to 60%. Learn more in the Compile Class documentation.
Crosswind includes a comprehensive test suite with 1300+ tests:
# Run all tests
bun test
# Run specific test files
bun test test/performance.test.ts
# Run tests in watch mode
bun test --watch- Core Functionality: Parser, generator, scanner, builder
- Utilities: Layout, typography, colors, spacing, grid, flexbox
- Variants: Responsive, state, pseudo-elements, combinations
- Advanced Features: Shortcuts, custom rules, arbitrary values
- Performance: Benchmarks for generation speed and memory efficiency
- Edge Cases: Invalid inputs, complex nesting, duplicate handling
Crosswind is designed for speed. We've benchmarked against other popular utility-first CSS frameworks to demonstrate our performance advantages.
Our comprehensive benchmark suite (20 tests) compares Crosswind with UnoCSS, Tailwind CSS v3, and Tailwind CSS v4.
| Scenario | Crosswind | UnoCSS | Tailwind v3 | Tailwind v4 | Winner |
|---|---|---|---|---|---|
| Simple Utilities (10 classes) | 2.75µs | 31.58µs | 14.32ms | 46.47ms | Crosswind ⚡ |
| Complex Utilities (11 classes) | 8.61µs | 43.77µs | 14.25ms | 39.26ms | Crosswind ⚡ |
| Arbitrary Values (10 classes) | 41.71µs | 64.44µs | 15.52ms | - | Crosswind ⚡ |
| Real-world Components (~60 classes) | 25.26µs | 97.71µs | 16.12ms | 45.07ms | Crosswind ⚡ |
| Large Scale (500 classes) | 94.89µs | 201.30µs | 14.51ms | 40.06ms | Crosswind ⚡ |
| CSS Output (1000 values) | 1.50ms | 115.59ms | 16.03ms | - | Crosswind ⚡ |
| Color Utilities (330 classes) | 100.85µs | 526.82µs | 12.89ms | 37.27ms | Crosswind ⚡ |
| Responsive (500 classes) | 100.16µs | 211.39µs | 12.86ms | 41.07ms | Crosswind ⚡ |
| Interactive States (440 classes) | 260.75µs | 1.16ms | 13.84ms | 38.06ms | Crosswind ⚡ |
| Duplicate Handling (6000 items) | 43.19µs | 1.81ms | 18.47ms | 48.11ms | Crosswind ⚡ |
| Typography (50 classes) | 16.06µs | 94.37µs | 14.37ms | 39.33ms | Crosswind ⚡ |
| Flexbox (50 classes) | 13.77µs | 88.62µs | 13.04ms | 42.38ms | Crosswind ⚡ |
| Grid (55 classes) | 59.89µs | 118.31µs | 15.10ms | 39.00ms | Crosswind ⚡ |
| Stacked Variants (40 classes) | 73.43µs | 148.79µs | 15.65ms | 41.11ms | Crosswind ⚡ |
| Transforms (55 classes) | 78.39µs | 100.85µs | 13.76ms | 44.34ms | Crosswind ⚡ |
| Transitions (30 classes) | 12.96µs | 66.47µs | 14.38ms | 36.46ms | Crosswind ⚡ |
| Border & Ring (45 classes) | 12.55µs | 90.45µs | 10.52ms | 40.58ms | Crosswind ⚡ |
| Shadow & Effects (35 classes) | 6.92µs | 62.12µs | 10.89ms | 36.62ms | Crosswind ⚡ |
| Incremental Generation (200 classes) | 73.91µs | 196.35µs | 14.07ms | 35.58ms | Crosswind ⚡ |
| Full Project (~800 classes) | 649.87µs | 1.38ms | 14.41ms | - | Crosswind ⚡ |
- Crosswind wins 20/20 benchmarks vs all competitors
- Simple utilities: 11x faster than UnoCSS, 5,200x faster than Tailwind v3
- Typography: 6x faster than UnoCSS
- Flexbox: 6.4x faster than UnoCSS
- Shadow & Effects: 9x faster than UnoCSS
- Border & Ring: 7x faster than UnoCSS
- Color utilities: 5x faster than UnoCSS
- Interactive states: 4.5x faster than UnoCSS
- Duplicate handling: 42x faster than UnoCSS
- CSS output generation: 77x faster than UnoCSS
- Full project simulation: 2.1x faster than UnoCSS, 22x faster than Tailwind v3
You can run the benchmarks yourself to see the performance on your hardware:
# Run the comprehensive benchmark suite
bun run benchmark
# Or run from the packages/crosswind directory
cd packages/crosswind
bun run benchmarkAll benchmarks use Mitata for accurate measurements and run on Bun runtime. Results may vary based on your hardware.
To contribute to Crosswind development:
# Clone the repository
git clone https://github.com/cwcss/crosswind.git
cd crosswind
# Install dependencies
bun install
# Run tests
bun test
# Run tests in watch mode
bun test --watch
# Run performance benchmarks
bun test test/performance.test.ts
# Type check
bun run typecheck
# Build the package
bun run buildFor comprehensive documentation, visit crosswind.stacksjs.org
Please see our releases page for more information on what has changed recently.
Please see CONTRIBUTING for details.
We welcome contributions! Whether it's:
- 🐛 Bug reports and fixes
- ✨ New utility classes or features
- 📝 Documentation improvements
- ⚡️ Performance optimizations
- 🧪 Additional test coverage
For help, discussion about best practices, or any other conversation that would benefit from being searchable:
For casual chit-chat with others using this package:
Join the Stacks Discord Server
“Software that is free, but hopes for a postcard.” We love receiving postcards from around the world showing where Stacks is being used! We showcase them on our website too.
Our address: Stacks.js, 12665 Village Ln #2306, Playa Vista, CA 90094, United States 🌎
We would like to extend our thanks to the following sponsors for funding Stacks development. If you are interested in becoming a sponsor, please reach out to us.
The MIT License (MIT). Please see LICENSE for more information.
Made with 💙
