Parcel vs Rolldown

Parcel is a free, open source, zero-configuration build tool for web projects. It handles HTML, CSS, JavaScript, TypeScript, JSX, Flow, images, fonts, videos, Sass, SVG, Vue, Node, Electron, GraphQL, MDX, XML and other file types out of the box. It can automatically install plugins and development dependencies for additional file types. For development, Parcel includes an HTTPS server with an API proxy and automatically updates code in the browser, with React Fast Refresh and Vue hot-reloading integrations. Terminal and browser diagnostics include syntax-highlighted code frames, hints and documentation links. Production features include tree shaking, minification, image optimization, code splitting, content hashing, and Gzip and Brotli compression. Builds use worker threads and caching, with lazy development builds also supported. Parcel can target declared browser environments, handle workers, build libraries for multiple targets and build monorepos with one command. A plugin system and programmatic API support customization and integration into existing build systems. Its development server builds only one target at a time and defaults to a modern browser target; compression is not enabled by default.

Rolldown is a free, open-source JavaScript bundler written in Rust and designed as the unified bundler powering Vite 8+. Its Rollup-compatible plugin API can reuse most existing Rollup plugins. Built-in capabilities include TypeScript and JSX transforms, syntax lowering, module resolution, ESM and CommonJS interoperability, define, inject, and minification. It can handle mixed ESM and CommonJS module graphs and supports configurable manual code splitting. Install commands are provided for npm, pnpm, yarn, bun, and vp. Prebuilt binaries are listed for Linux, Windows, Apple platforms, Android, and other targets; where none is distributed, a Wasm build or building from source are options. The guide recommends using Rolldown through Vite for most applications and points library authors to tsdown. Module types are experimental, and the JavaScript build() API may change in patch releases. The troubleshooting guide says Windows file-system access can slow builds, particularly when transforms run without plugins. An online REPL is linked, along with GitHub, Discord, and contribution resources. VoidZero Inc. holds the copyrights, funds development, and directs the project; it states Rolldown remains open source and MIT-licensed.