ProGuard has moved to Github now: https://github.com/Guardsquare/proguard
ProGuard is a free Java class file shrinker, optimizer, obfuscator, and preverifier. It detects and removes unused classes, fields, methods, and attributes. It optimizes bytecode and removes unused instructions. It renames the remaining classes, fields, and methods using short meaningless names.
ProGuard is useful for making code more compact and more efficient, on the desktop, on tablets, on smartphones...