name	tsdown
description	tsdown fast TypeScript library bundler powered by Rolldown and Oxc. Use when bundling TypeScript libraries, configuring entry points, or generating .d.ts declaration files.
metadata	{"author":"Anthony Fu","version":"2026.1.28","source":"Generated from https://github.com/rolldown/tsdown, scripts located at https://github.com/antfu/skills"}

tsdown is a next-generation TypeScript library bundler built on Rolldown and Oxc. It provides blazing-fast builds, automatic .d.ts generation, and seamless migration from tsup. Supports Rolldown/Rollup/Unplugin plugins and features smart dependency handling.

The skill is based on tsdown v0.20.1, generated at 2026-01-28.

Anthony's Preferences:

Build pure-ESM packages, avoid CJS
Always enable dts option for type declarations
Enable exports option for auto-generated package exports

Core

Topic	Description	Reference
Configuration	Config file setup, defineConfig, multiple configs	core-config
CLI	Command-line interface and options	core-cli
Entry Points	Entry files, aliases, glob patterns	core-entry

Build Options

Topic	Description	Reference
Output	Format (ESM/CJS/IIFE/UMD), directory, target, platform	options-output
Declaration Files	.d.ts generation, isolatedDeclarations, sourcemaps	options-dts
Dependencies	External, noExternal, dependency bundling	options-dependencies
Package Exports	Auto-generating exports, main, module fields	options-package-exports

Features

Topic	Description	Reference
Optimization	Tree shaking, minification, sourcemaps	features-optimization
Shims	CJS/ESM compatibility shims	features-shims
Unbundle Mode	Bundleless transpile-only builds	features-unbundle
Watch Mode	Auto-rebuild on file changes	features-watch

Advanced

Topic	Description	Reference
Plugins	Rolldown, Unplugin, Rollup, Vite plugins	advanced-plugins
Hooks	Build lifecycle hooks	advanced-hooks
Programmatic API	Using tsdown from code	advanced-programmatic
Rolldown Options	Customizing inputOptions and outputOptions	advanced-rolldown-options