Closure Compiler is a JavaScript optimizing compiler. It parses your JavaScript, analyzes it, removes dead code and rewrites and minimizes what's left. It also checks syntax, variable references, and types, and warns about common JavaScript pitfalls. It is used in many of Google's JavaScript apps, including Gmail, Google Web Search, Google Maps, and Google Docs.

ClojureScript compiler and core runtime library.

Wro4j Extensions

Javascript/CSS bundling and compressing tool for java web apps. By using jawr resources are automatically bundled together and optionally minified and gzipped.

Maven plugin to compress and merge resources like JavaScript and CSS files.

Spring Soy View AJAX Compiler

Silksmith

A Dependency Calculcator for files that use goog.provide and goog.require calls

Maven plugin for compressing JS files at build time

An extensible asset pipeline for Clojure web applications