Open Source Mobile Operating Systems Decompilers

Some of Bytecode Viewer features are that it provides Java Decompiling with Six different decompilers (DJ-GUI/Core, Procyon, CFR, Fernflower, Krakatau, and JADX-Core). Bytecode Decompiling with CFIDE. Android APK integrated with Dex2Jar. Securely launch Java applications and insert hooks via EZ-Injection. Scan for malicious code with the Malicious Code Scanner plugin. Export as DEX, Jar, Class, Zip or Java Source File. Open Android APKs, Android DEX, Java Class Files and Java Jars. (WAR & JSP Support!). Extensively configurable, over 100+ settings! Works seamlessly with all Operating Systems. Integrates BCV into Windows by installing it, it'll associate all .class, .dex and .apk to open with BCV. You can view Jar & APK Resources with ease by APKTool.jar integration. It is 100% free and open sourced under GPL v3 CopyLeft.

APK Explorer & Editor is a free, open-source Android application designed for inspecting and modifying APK files. It allows users to browse the contents of installed applications or APK packages stored on their devices. The software can extract resources such as icons, fonts, graphics, and XML files. Its integrated editors support modifying text and binary XML resources. Users can replace or delete resources and reassemble modified Smali code into DEX files. The application also includes tools for decoding resource tables and managing split APKs. Modified applications can be rebuilt and signed for installation. APK Explorer & Editor provides a portable toolkit for Android application inspection, customization, and package management.

dxcut is a library for reading, editing, and writing dex and odex files which contain the class definition and Dalvik bytecode used by the Android operating system. This project includes a disassembler/decompiler, dex optimizer, and hooking utils.