Java Decompiler, Disassembler and Bytecode debugger. Decompiler supports Java 5 (e.g. generics, for-each loops etc). Debugger allows user to step through each bytecode and view program state. Contains Swing GUI.
Hex Editor VB is a hexadecimal editor for Windows. It allows to view and/or edit files, process memory and physical/logical disks. It includes lots of functions like file management, process management, advanced conversions between bases, disassembler...
jbytecode is a Java bytecode disassembler/assembler written in Python. Dissasembly code is aligned with Java bytecodes in the class file so modification and re-assembly is always possible, even when class is obfuscated.
JasminParser is a Jasmin (Java Assembler, .j file) compiler based on the Apache BCEL. JasminParser provides a disassembler and an assembler to convert java classes and jasmin files to each other.
JReversePro is a Java Decompiler / Disassembler written in Java. Facility to view the ConstantPool contents is available. AWT, Swing and command-line versions are present.
JTools.Ruby is easy way to access Java 2 class-files via scripts written in Ruby language. There are class-file disassembler, assembler and simple Ruby to Java bytecode compiler. The work is at the start point.
JEST will be the Java bytecode engineering Swiss-Army Jackhammer.
It will include a disassembler, class browser, obfuscator, optimizer, class editor, and bytecode debugger, and have an intuitive GUI.