Google Closure Compiler vs Rspack

Google Closure Compiler optimizes JavaScript by analyzing code, removing dead code, and rewriting and minimizing what remains. It can also check syntax, references, and types, and warn about illegal JavaScript, risky operations, and common pitfalls. Google says smaller output files can help applications load faster and reduce bandwidth needs. Compilation options include WHITESPACE_ONLY, SIMPLE, and ADVANCED; the repository README also lists BUNDLE. ADVANCED applies aggressive transformations and symbol renaming to improve compression, so preserving program behavior requires care. The project is available as a command-line Java application, a library used through Bazel, and an NPM package. Released JARs are distributed through Maven. The repository documents Maven, NPM, Bazel, command-line Java, and a NodeJS API. Building the compiler requires Java 21 or later, NodeJS, Git, and Bazelisk. Its input restrictions include use of goog.module() and goog.require(), and ES6 import/export support is not actively maintained. The NPM packages are built and distributed by an open source contributor, not Google. The compiler is free.

Rspack is a free, open-source bundler for web projects, built with Rust and TypeScript. Its parallelized architecture supports parallel builds, while incremental compilation is used to improve hot module replacement. Rspack updates the webpack API with the aim of supporting webpack replacement, but it does not promise full API compatibility; it prioritizes commonly used APIs and adds others based on user needs. It works with almost all community loaders, and over 85% of the 50 most downloaded webpack plugins can be used with it or have an alternative. Built-in capabilities include code splitting, tree shaking, asset management, a development server, SWC, Lightning CSS, and a JavaScript build API. Documented integrations cover React, React Server Components, Preact, Vue, Next.js, Node.js applications, NestJS, Solid, Svelte, and Rstest. Custom plugins and loaders can be written in JavaScript or Rust. Rspack 1.0 was released in August 2024 and is described as production-ready. It is available for Linux, macOS, and Windows, as well as web and self-hosted environments. The software is released under the MIT license; questions can be directed to Discord or GitHub Discussions.