APK Editor Studio - APK Editor Studio is an open-source Android application editor that allows you to edit APKs with the help of reverse engineering.
Java Decompiler - Yet another fast Java decompiler
JADX - JADX is a decompilation tool that can produce Java Source code from Dex and Apk files, being capable of providing human-readable java classes, it reverses AndroidManifest.
Decompiler.com - Online Java and Android decompiler. Just drag and drop .JAR or .APK file and browse decompiled content online.
Apktool - Apktool is an all-in-one tool that can extract all the resources inside an APK.
ILSpy - ICSharpCode. Decompiler. Console..