APK Studio - APK Studio is an open-source Integrated Development Environment that allows you to recompile and decompile Android applications with its unified interface.
Decompiler.com - Online Java and Android decompiler. Just drag and drop .JAR or .APK file and browse decompiled content online.
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.
dnSpy - .NET assembly editor, decompiler, and debugger
Apktool - Apktool is an all-in-one tool that can extract all the resources inside an APK.
ILSpy - ICSharpCode. Decompiler. Console..