Rslib vs tsdown
Rslib
lib.rsbuild.devtsdown
tsdown.devSide by side
| Figure | Rslib | tsdown |
|---|---|---|
| Price from | Free | — |
| Free plan | Yes | — |
| Free trial | — | — |
| Open source | — | — |
| Web | Yes | Yes |
| Windows | Yes | — |
| macOS | Yes | — |
| Linux | Yes | — |
| API | Yes | — |
| Plans published | 1 | 0 |
| Spec score · JavaScript Build Tools | 8.6 (#2) | 7.0 (#27) |
| Build engine | Rslib is based on Rsbuild and uses Rspack, with SWC and Lightning CSS among the Rust-based tools it integrates. | tsdown is built on Rolldown, a Rust-based bundler. |
| License | Rslib is free and open source software released under the MIT license. | The project website states that tsdown is released under the MIT License. |
| Maker | The official site identifies ByteDance Inc. in its copyright notice. | The project credits VoidZero Inc. and contributors. |
| Output formats | Rslib supports ESM, CJS, UMD, Module Federation, and IIFE output formats. | It supports ESM, CJS, IIFE, and UMD output formats. |
| Purpose | Rslib is an Rsbuild-based tool for developing JavaScript libraries and UI component libraries. | tsdown is a bundler designed for building TypeScript and JavaScript libraries. |
| Runtime requirement | Rslib v1 requires Node.js 20.19+ or 22.12+. | The guide requires Node.js ^22.18.0, ^24.11.0, or >=26.0.0 to run tsdown and says Bun and Deno support is experimental. |
Plans
In their own words
Rslib
Rslib is a free, open-source tool for developing JavaScript packages and UI component libraries. Based on Rsbuild and powered by Rspack, it integrates Rust-based tools including SWC and Lightning CSS. It supports bundle and bundleless build modes and outputs ESM, CJS, UMD, Module Federation, and IIFE formats. Framework integrations support component libraries for React, Vue, Svelte, and Solid. Rslib can generate TypeScript declaration files, including isolated declarations, though declaration generation is not enabled by default. Plugin support includes Rsbuild, Rspack, and webpack plugins. Its development integrations include Rstest for testing, Storybook for component development, Rspress for documentation and component previews, and Rsdoctor for build analysis. The quick-start guide lists Node.js, Deno, and Bun as runtime options, while Rslib v1 requires Node.js 20.19+ or 22.12+. It is available for API, Linux, macOS, web, and Windows, and is released under the MIT license.