Bytecode Viewer

Bytecode Viewer is an advanced Java bitcode viewer, GUI Java Decompiler, GUI bytecode Editor, GUI Smali, GUI Baksmali, GUI APK Editor, GUI Dex Editor, GUI APK Decompiler, GUI DEX Decompiler, GUI Procyon Java Decompiler, GUI Krakatau, GUI CFR Java Decompiler, GUI FernFlower Java Decompiler, GUI DEX2Jar, GUI Jar2DEX, GUI Jar-Jar, Hex Viewer, Code Searcher, debugger and more.

It is written entirely in Java

There is also a plugin system that allows you to interact with the loaded classfiles, for example you can write a String deobfuscator, a malicious code searcher, or anything else you can think of.

You can either use one of the pre-written plugins or write your own. It supports groovy scripting. Once the plugin is activated, it will run the plugin with the ClassNode ArrayList of each class embedded in the BCV, this allows the user to completely manipulate it using ASM.