# Tsdown > tsdown fast TypeScript library bundler powered by Rolldown and Oxc. Use when bundling TypeScript libraries, configuring entry points, or generating .d.ts declaration files. Use when this capability is needed. - Skill: `tomevault-io/tsdown-3` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/tsdown-3` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/tsdown-3/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/tsdown-3 --- 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](references/core-config.md) | | CLI | Command-line interface and options | [core-cli](references/core-cli.md) | | Entry Points | Entry files, aliases, glob patterns | [core-entry](references/core-entry.md) | ## Build Options | Topic | Description | Reference | |-------|-------------|-----------| | Output | Format (ESM/CJS/IIFE/UMD), directory, target, platform | [options-output](references/options-output.md) | | Declaration Files | .d.ts generation, isolatedDeclarations, sourcemaps | [options-dts](references/options-dts.md) | | Dependencies | External, noExternal, dependency bundling | [options-dependencies](references/options-dependencies.md) | | Package Exports | Auto-generating exports, main, module fields | [options-package-exports](references/options-package-exports.md) | ## Features | Topic | Description | Reference | |-------|-------------|-----------| | Optimization | Tree shaking, minification, sourcemaps | [features-optimization](references/features-optimization.md) | | Shims | CJS/ESM compatibility shims | [features-shims](references/features-shims.md) | | Unbundle Mode | Bundleless transpile-only builds | [features-unbundle](references/features-unbundle.md) | | Watch Mode | Auto-rebuild on file changes | [features-watch](references/features-watch.md) | ## Advanced | Topic | Description | Reference | |-------|-------------|-----------| | Plugins | Rolldown, Unplugin, Rollup, Vite plugins | [advanced-plugins](references/advanced-plugins.md) | | Hooks | Build lifecycle hooks | [advanced-hooks](references/advanced-hooks.md) | | Programmatic API | Using tsdown from code | [advanced-programmatic](references/advanced-programmatic.md) | | Rolldown Options | Customizing inputOptions and outputOptions | [advanced-rolldown-options](references/advanced-rolldown-options.md) | ## Recipes | Topic | Description | Reference | |-------|-------------|-----------| | Framework Support | Vue and React library bundling | [recipes-frameworks](references/recipes-frameworks.md) | | Migration | Migrating from tsup | [recipes-migration](references/recipes-migration.md) | --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/ummitkin) — claim your Tome and manage your conversions.