Apktool

A tool for reverse engineering 3rd party, closed, binary Android apps. It can decode resources to nearly original form and rebuild them after making some modifications. It also makes working with an app easier because of the project like file structure and automation of some repetitive tasks like building apk, etc. It is NOT intended for piracy and other non-legal uses. It could be used for localizing, adding some features or support for custom platforms, analyzing applications and much more. The decode option on Apktool can be invoked either from d or decode. In order to run a rebuilt application. You must resign the application. Android documentation can help with this. As you probably know, Android apps utilize code and resources that are found on the Android OS itself. These are known as framework resources and Apktool relies on these to properly decode and build apks.