jad

Jad is primarily known as a Java decompiler, a software tool that converts Java bytecode in .class files back into readable Java source code. It was popular in the 1990s and 2000s as a means to recover source when the original Java source files were unavailable. Jad accepts individual class files or archives such as JARs and can output Java source to a file or standard output. It offers both a command-line interface and a graphical user interface in some distributions, and it can reconstruct many language constructs including classes, methods, and control flow, though with limitations.

Because decompiling is not guaranteed to restore the exact original source, Jad can struggle with optimizations, compiler-generated artifacts, and obfuscated names. Local variables often receive generic names, and comments or formatting are not recovered. It may also fail to reconstruct complex or heavily modernized language features, leading to decompiled output that requires manual review.

Development of Jad has slowed in recent years, and modern decompilers have largely supplanted it in many workflows. Despite this, Jad remains referenced in legacy documentation and projects and can still be used for basic decompilation tasks.

In other contexts, "Jad" (often capitalized as JAD) can be a given name or initialism in various cultures and may refer to unrelated projects or organizations. When encountered in text, the meaning is usually clarified by surrounding context or a disambiguation note.