Google Closure Compiler vs webpack

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.

webpack is a free, open-source static module bundler for modern JavaScript applications. It builds a dependency graph and combines modules into bundles, with code splitting for on-demand loading. Built-in support covers JavaScript, JSON, WebAssembly, CSS and HTML. Loaders transform sources such as Sass into CSS or TypeScript into JavaScript, while plugins customize compilation through lifecycle hooks. ModuleFederationPlugin lets independently built applications share modules at runtime. Since version 4.0.0, webpack can run without a configuration file, although it remains highly configurable. Interfaces include the CLI, Node API, loader API and plugin API, and documentation covers integrations with Browserify, Brunch, Grunt, Gulp, Mocha and Karma. The project recommends local npm installation and a fresh Node.js installation; command-line use from webpack v4 onward also requires webpack-cli. The MIT-licensed software supports tree shaking and source maps. CSP is not enabled by default, and native CSS and HTML support are experimental.