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Created October 1, 2025 07:32
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Some notes on tools and techniques for reverse engineering Java programs.
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reverse-engineering-java.md

Reverse Engineering Java

Some notes on tools and techniques for reverse engineering Java programs.

Table of Contents

Unsorted

  • TODO: Enumerate existing tools and include them here, including:
    • Mainstream / Actively Maintained Decompilers
      • CFR (popular modern Java decompiler, supports new Java features)
      • Procyon (focuses on Java 5+ features, strong with lambdas/generics)
      • Fernflower (bundled in IntelliJ IDEA, originally by Stiver)
      • Quiltflower (active fork of Fernflower)
      • JD-GUI (classic standalone GUI decompiler)
      • JADX (for Android APKs/Dex, decompiles to Java)
    • Bytecode -> Source Alternatives / Wrappers
      • Bytecode Viewer (all-in-one GUI, integrates CFR, Procyon, Fernflower, etc.)
      • Krakatau (bytecode assembler/disassembler/decompiler)
      • Luyten (GUI frontend for Procyon)
      • Androguard (Android reverse engineering toolkit, Python-based)
      • JAD (historical, one of the earliest Java decompilers)
    • Related / Bytecode Manipulation Frameworks
      • ASM (bytecode manipulation and analysis framework)
      • BCEL (Byte Code Engineering Library)
      • JBE (Java Bytecode Editor)
    • General Reverse Engineering Frameworks with JVM Support
      • Radare2 / r2ghidra-dec (general RE frameworks with some JVM/bytecode support)
    • etc?
  • https://github.com/JetBrains/fernflower

    • Fernflower

    • Decompiler from Java bytecode to Java, used in IntelliJ IDEA.

    • Fernflower is the first actually working analytical decompiler for Java and probably for a high-level programming language in general. Naturally, it is still under development.

    • Fernflower was originally written by Stiver.

See Also

My Other Related Deepdive Gist's and Projects

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