Apps similar to YUI Compressor include Closure Compiler, which is free and open source. Other options are JavaScript Obfuscator, Terser, UglifyJS and BeautifyTools. In total there are five apps like YUI Compressor for the web, self-hosting, Mac, Windows and Linux.
The Closure Compiler is a tool for making JavaScript download and run faster. It is a true compiler for JavaScript. Instead of compiling from a source language to machine code, it compiles from JavaScript to better JavaScript.
United States
This webapp can obfuscate your JavaScript with various levels of protection, including: self-defending code, domain lock and debug protection. It's based on a open source (Node.js) project, so you can run on your own server if you like.
Portugal
EU
Romania