Shrinks and obfuscates, with template-based configuration. Comes with an Ant task, a J2ME WTK plugin, and a tool to de-obfuscate stack traces. [Open source, GPL]

Bytecode obfuscator configurable to run through Ant build scripts. [Freeware, core library is open source, LGPL]

A Bytecode Obfuscator with third-generation control-flow transformations. [Open source]

Can be used to optimize, obfuscate and/or decompile code. [Open Source, GPL]

Removes unused code and data then obfuscates symbolic names in class files. [Commercial]

Java obfuscator with flow obfuscation, string literal encryption, scripting, Ant integration, incremental obfuscation, obfuscated line numbers, J2ME plugin and stack trace translation. Also removes unused classes, fields and methods. [Commercial]

Highly-configurable Java bytecode obfuscator with support for Java 2, reflection and scripting. [Open Source, LGPL]

Obfuscates. Updated version of RetroGuard. Can be run from the command-line or using a GUI. [Open source, GPL]

Removes unnecessary classes and obfuscates applications, applets, and servlets. Supports encryption of string constants. [Freeware]

Shrinks and obfuscates jar files. Runs from the command line or as an Ant task. [Open source, BSD]