/tsdown

Features

Tree Shaking

Enabled by default - removes unused code.

defineConfig({
  treeshake: true,   // Default
  treeshake: false,  // Disable
})

Minification

defineConfig({
  minify: true,
})

Uses Oxc (fast, currently alpha).

Source Maps

defineConfig({
  sourcemap: true,
})

Auto-enabled if declarationMap: true in tsconfig.json.

Shims

CJS in ESM

__dirname and __filename not available in ESM:

defineConfig({
  shims: true,  // Provides __dirname, __filename
})

require in ESM

Auto-injected when platform: 'node':

// Generated:
const require = createRequire(import.meta.url)

ESM in CJS

Always enabled - import.meta.url, import.meta.dirname, import.meta.filename work in CJS.

CJS Default Export

When CJS output has only default export:

// Source
export default function greet() {}

// CJS Output
module.exports = greet

// Declaration
declare function greet(): void
export = greet

Unbundle Mode

Transpile-only - preserves file structure:

defineConfig({
  entry: ['src/index.ts'],
  unbundle: true,
})

Input:

src/
  index.ts
  mod.ts

Output:

dist/
  index.js
  mod.js

Watch Mode

defineConfig({
  watch: true,
  // Or specific paths
  watch: ['./src', './lib'],
})

tsdown --watch
tsdown --watch ./src
tsdown --ignore-watch node_modules

Post-Build Command

tsdown --watch --on-success "node dist/index.mjs"

Copy Assets

tsdown --copy public

Environment Variables

tsdown --env.NODE_ENV=production
tsdown --env-file .env.production
tsdown --env-prefix APP_

Node Protocol

Control Node.js built-in imports:

defineConfig({
  nodeProtocol: true,     // fs → node:fs
  nodeProtocol: 'strip',  // node:fs → fs
  nodeProtocol: false,    // Keep as-is (default)
})

CSS

defineConfig({
  css: {
    splitting: false,      // Single CSS file
    fileName: 'styles.css',
  },
})

CSS targeting (requires unplugin-lightningcss):

pnpm add -D unplugin-lightningcss

JSX

Built-in support via Rolldown:

defineConfig({
  inputOptions: {
    transform: {
      jsx: 'react',  // Classic transform
    },
  },
})

Framework Support

React

// tsdown.config.ts
import { defineConfig } from 'tsdown'

export default defineConfig({
  entry: ['./src/index.ts'],
  platform: 'neutral',
  dts: true,
})

React Compiler:

pnpm add -D @rollup/plugin-babel babel-plugin-react-compiler

import pluginBabel from '@rollup/plugin-babel'

defineConfig({
  plugins: [
    pluginBabel({
      babelHelpers: 'bundled',
      parserOpts: {
        sourceType: 'module',
        plugins: ['jsx', 'typescript'],
      },
      plugins: ['babel-plugin-react-compiler'],
      extensions: ['.js', '.jsx', '.ts', '.tsx'],
    }),
  ],
})

Vue

pnpm add -D unplugin-vue vue-tsc

import { defineConfig } from 'tsdown'
import Vue from 'unplugin-vue/rolldown'

export default defineConfig({
  entry: ['./src/index.ts'],
  platform: 'neutral',
  plugins: [Vue({ isProduction: true })],
  dts: { vue: true },
})

Quick Start Templates

npx create-tsdown@latest -t vue
npx create-tsdown@latest -t react
npx create-tsdown@latest -t react-compiler