konloch/bytecode-viewer

Bytecode Viewer (BCV) is a Java-based tool for reverse engineering, meaning it helps you look inside compiled Java and Android application files to understand what they actually do, even without the original source code. You use it by simply dragging and dropping a file (such as a Jar, APK, DEX, or ZIP) into the program, and it automatically begins decoding it for you. One of its standout features is that it bundles six different Java decompilers, Krakatau, CFR, Procyon, FernFlower, JADX, and JD-GUI, all in one place. A decompiler takes compiled machine-readable code and attempts to reconstruct human-readable source code from it. Having six means you can compare outputs side by side, since different decompilers sometimes handle tricky code better than others. It also includes three bytecode disassemblers and two assemblers (Krakatau and Smali/BakSmali), plus tools for converting Android APK files into a Java-readable format via Dex2Jar and Enjarify. Beyond viewing code, BCV supports editing and recompiling Java and bytecode directly within the tool, making it useful for patching applications. A plugin system lets you write your own scripts in Java or JavaScript to automate tasks like searching for suspicious strings or deobfuscating code. It also ships with advanced search functionality, a command-line interface for batch processing, and a dark mode with multiple themes. The interface has been translated into over 30 languages including Arabic, German, Japanese, Mandarin, Russian, and Spanish. You can export results as a runnable Jar, Zip, or APK. To get started, download the latest release and run the Jar file, or launch it via the command line if needed.