If you're bundling TypeScript libraries and tsup feels familiar, this is the Rolldown-powered successor that handles ESM, CJS, IIFE, and UMD outputs with type declaration generation built in. It requires Node 22+ to run the bundler itself, but you can target older runtimes in your output. The dependency handling is granular with neverBundle, alwaysBundle, and onlyBundle options, and it includes framework-specific recipes for React, Vue, Solid, and Svelte. The migration path from tsup is intentionally smooth with a dedicated migration tool. Worth noting the experimental CSS pipeline with preprocessors and modules support, plus the ability to bundle standalone executables. It's opinionated enough to work out of the box but exposes Rolldown options when you need control.
npx skills add https://github.com/rolldown/tsdown --skill tsdown