tsdown

Bundle TypeScript and JavaScript libraries into ESM, CJS, IIFE, and UMD formats.

Updated Aug 27, 2026
One-click install
npx skills add https://github.com/ajiu9/skills --skill tsdown-ajiu9
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: tsdown
Source: https://github.com/ajiu9/skills/tree/main/skills/tsdown
Command: npx skills add https://github.com/ajiu9/skills --skill tsdown-ajiu9

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

tsdown bundles TypeScript and JavaScript libraries with blazing-fast speed powered by Rolldown and Oxc to streamline multi-format builds and DTS generation.

Core Features & Use Cases

  • Multi-format bundling (esm, cjs, iife, umd)
  • Type declaration generation (dts) and exports
  • Workspace/monorepo support with migration guidance from tsup

Quick Start

Install tsdown and run a build to produce ready-to-publish bundles.

Frequently Asked Questions about tsdown

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I bundle TypeScript libraries into multiple formats like esm and cjs?

You can bundle TypeScript libraries into esm and cjs formats using tsdown, which leverages Rolldown and Oxc to produce ready-to-publish multi-format outputs including iife and umd.

What is the best way to generate dts type declarations for a JavaScript library?

The best way to generate dts type declarations is using tsdown, which natively produces type declarations and handles exports alongside multi-format bundling for library authors.

Can I migrate my existing tsup build configuration to a faster bundler?

Yes, you can migrate your existing tsup build configuration to tsdown, which provides specific migration guidance and supports similar features like multi-format builds and programmatic or CLI usage.

Does tsdown support workspace monorepo builds for multi-format outputs?

Yes, tsdown supports workspace monorepo builds for multi-format outputs, allowing you to bundle TypeScript and JavaScript libraries across packages with per-format configuration.

How do I configure per-format build settings when bundling a TS library?

You configure per-format build settings when bundling a TS library through tsdown, which allows you to specify distinct configurations for esm, cjs, iife, and umd outputs.