Parcel.js

Parcel, or Parcel.js, is a zero configuration web application bundler. Parcel supports many languages and file types out of the box, from web technologies like HTML, CSS, and JavaScript, to assets like images, fonts, and videos. When a file type isn't included by default, Parcel will automatically install all of the necessary plugins and dev dependencies for the user.


Parcel builds code in parallel using worker threads, utilizing all of the cores on the user's machine. Everything is cached, so as to never build the same code twice.

Parcel's JavaScript compiler, CSS transformer, and source maps implementation are written in Rust for maximum performance (presented as 10-20x faster than other JavaScript-based tools). Parcel's JavaScript compiler is built on SWC, which handles transpiling JavaScript, JSX, and TypeScript. On top of SWC, Parcel implements dependency collection, bundling, scope hoisting, tree shaking, Node emulation, hot reloading, and more. Parcel's CSS transformer and minifier is built in Rust on top of the browser-grade CSS parser used in Firefox.

Parcel automatically tracks all of the files, configuration, plugins, and dev dependencies that are involved in a build, and granularly invalidates the cache when something changes. It integrates with low-level operating system APIs to determine what files have changed in milliseconds, no matter the project size.