Rolldown

Rolldown is a Rust port of Rollup being developed by the Vite team. It aims to provide Rollup's excellent bundling with esbuild-like performance.

Key Features

• Rollup Compatible: Same API as Rollup
• Rust Performance: 10-100x faster than Rollup
• Vite Integration: Will replace Rollup in Vite
• Plugin Compatibility: Compatible with Rollup plugins
• Tree Shaking: Industry-leading dead code elimination

Status (2025)

• Development: Active development, not production-ready
• Vite: Planned to replace Rollup in future Vite versions
• API: Following Rollup's API closely
• Performance: Showing promising benchmarks

Installation

# Not yet published to npm
# Follow GitHub for updates

Expected API

Based on Rollup compatibility:

// rolldown.config.js
export default {
  input: 'src/index.ts',
  output: {
    file: 'dist/bundle.js',
    format: 'esm',
  },
  plugins: [
    // Rollup plugins should work
  ],
};

Performance Goals

Operation	Rollup	Rolldown (Goal)
Build	10s	0.5s
Rebuild	5s	0.1s
Plugin Processing	2s	0.05s

Architecture

Rust Core

• Fast parsing with SWC
• Parallel module processing
• Efficient tree-shaking

Plugin Compatibility

• Napi bridge for JS plugins
• Native Rust plugins for performance
• Gradual migration path

Comparison with Alternatives

Feature	Rolldown	Rollup	esbuild
Speed	Fast	Slow	Fastest
Ecosystem	Growing	Excellent	Limited
Tree Shaking	Excellent	Excellent	Good
API	Rollup-like	Stable	Different

Use Cases

Vite (Future)

Will power Vite production builds:

// vite.config.ts (future)
export default {
  build: {
    rollupOptions: {
      // These will use Rolldown
    },
  },
};

Library Bundling

Perfect for modern libraries:

export default {
  input: 'src/index.ts',
  output: [
    { file: 'dist/index.esm.js', format: 'esm' },
    { file: 'dist/index.cjs.js', format: 'cjs' },
  ],
};

Migration from Rollup

Compatibility Layer

Rolldown aims for 100% Rollup compatibility:

// Existing Rollup config should work as-is
import { rollup } from 'rolldown';

// Same API as Rollup
const bundle = await rollup({
  input: 'src/index.ts',
});

Plugin Migration

Most Rollup plugins should work without changes:

import resolve from '@rollup/plugin-node-resolve';
import typescript from '@rollup/plugin-typescript';

export default {
  plugins: [
    resolve(),
    typescript(),
  ],
};

Timeline

• 2024 Q4: Alpha release
• 2025 Q1: Beta release
• 2025 Q2: Vite integration
• 2025 Q3: Stable release

Following Development

• GitHub: rolldown-rs/rolldown
• Discord: Vite Discord server
• Twitter: Follow @youyuxi (Evan You)

Benefits for Vite

Unified Toolchain

Single tool for dev and prod:

• Dev: Vite's dev server
• Prod: Rolldown bundling

Better Performance

Faster production builds:

• 10-100x faster than Rollup
• Reduced CI/CD times

Plugin Compatibility

Use same plugins in dev and prod:

// Same plugins work in both modes
export default {
  plugins: [myPlugin()],
};

Resources

• GitHub: rolldown-rs/rolldown
• Rollup Docs: rollupjs.org
• Vite: vitejs.dev