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tsdown review

Free#11 of 27 in JavaScript Build Tools

A focused, open-source bundler for publishing TypeScript and JavaScript packages.

8.1/10Editor score
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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

tsdown is an open-source command-line bundler for TypeScript and JavaScript libraries. It is aimed at developers publishing reusable packages, from small utilities to larger libraries, with configuration designed to reduce build-tool setup. The tool runs as a development dependency in a Node.js-based build environment and is powered by Rolldown. Its library-oriented scope makes it a natural fit for package authors who need consistent output formats and generated declarations.

The build feature set covers TypeScript and JavaScript bundling, automatic TypeScript declaration generation, and ESM, CJS, IIFE, and UMD outputs. Tree shaking is enabled by default, while separate, inline, and hidden source maps support different debugging and distribution needs. tsdown also provides code splitting, JSON and WebAssembly asset processing, aliases, minification, externalization, and watch mode for automatic rebuilds. These capabilities give package maintainers control over both published artifacts and the development build cycle.

tsdown is free and open source under the MIT License. Its integration surface includes Rolldown, Rollup, Unplugin, and some Vite plugin support, with a plugin API listed among its category capabilities. The project documentation displays version 0.23.0. Choose tsdown if your priority is publishing TypeScript or JavaScript libraries with declarations, multiple module formats, and package-focused bundling. An application workflow that depends heavily on broader platform-specific tooling may be better served by a more general build system.

tsdown pros and cons

  • Where it wins
    • Generates TypeScript declarations automatically
    • Supports ESM, CJS, IIFE, and UMD outputs
    • Includes tree shaking, source maps, and code splitting
  • Where it doesn't
    • Focused on library workflows rather than general application builds
    • Requires a Node.js-based build environment
    • Plugin support varies across Rolldown, Rollup, Unplugin, and Vite

tsdown fact sheet, pricing and score →

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