An API and a graphical tool for inspection (viewing, searching and comparing) and manipulation (modification, obfuscation, refactoring of methods, fields, attributes and code) of classfiles for the Java platform.
Yet another Java obfuscation tool. This one has a bit of a different twist, in that it can obfuscate native methods by generating a .h file which #defines the original method names to the obfuscated ones. Built with Apache BCEL.