I have used the Closure Compiler for years (and contributed too!).<p>It is really a fantastic tool (along with the Closure Library and other members of the Closure family) for anyone that values maintainable, solid JS.<p>I can understand why it&#x27;s not more popular; it feels a lot like Java -- industrial strength, non-flashy, and perhaps a little boring. It&#x27;s also a little hard to setup for a real project (tutorials could be better).<p>It has been around since the creation of Gmail, and will be around to stay for years to come. (Though it has improved substantially over the years.)