tsdown - The Elegant Library Bundler

Fast TypeScript/JavaScript library bundler powered by Rolldown with multi-format output and type declaration generation.

- Supports bundling to ESM, CJS, IIFE, and UMD formats with automatic peer dependency externalization and tree shaking

- Generates TypeScript declaration files (.d.ts) with source map and compiler option control, plus experimental CSS pipeline with preprocessor and PostCSS support

- Includes watch mode, minification, source maps, unbundle mode for preserving directory structure, and framework-specific recipes for React, Vue, Solid, and Svelte

- Offers CLI commands, programmatic API, lifecycle hooks, workspace/monorepo support, and direct Rolldown option passthrough for advanced customization

- Provides migration tooling from tsup and experimental features for standalone executable bundling and package validation (publint, attw)

tsdown - The Elegant Library Bundler

Blazing-fast bundler for TypeScript/JavaScript libraries powered by Rolldown and Oxc.

When to Use

- Building TypeScript/JavaScript libraries for npm

- Generating TypeScript declaration files (.d.ts)

- Bundling for multiple formats (ESM, CJS, IIFE, UMD)

- Optimizing bundles with tree shaking and minification

- Migrating from tsup with minimal changes

- Building React, Vue, Solid, or Svelte component libraries

Quick Start

# Install
pnpm add -D tsdown