tsdown is an elegant library bundler built on Rolldown (Rust-based), providing a complete out-of-the-box solution for building TypeScript and JavaScript libraries. It handles source transformation, multiple output formats (ESM, CJS, IIFE, UMD), TypeScript declaration file generation, and package.json exports field generation with sensible defaults.
When to use: Building TypeScript libraries for npm, generating declaration files, producing dual ESM/CJS packages, bundling CLI tools, library development with watch mode, migrating from tsup.
When NOT to use: Application bundling (use Vite/Rolldown directly), server-side rendering frameworks (use framework bundlers), projects that need Webpack-specific features, simple scripts that need no bundling.
Bundler tsdown TypeScript construit sur Rolldown pour les bibliothèques et les packages. À utiliser lors du regroupement de bibliothèques TypeScript, de la génération de fichiers de déclaration ou de la publication de packages npm. À utiliser pour tsdown, bundler, rolldown, dts, déclaration, library-build, esm, cjs, treeshake. Source : oakoss/agent-skills.