Hi tar is an old format with its name derived from Tape ARchive file. It can contain many files and can be unpacked to show or retrieve is contents. It cannot be converted into something it is not. If the tar contains .apk files(android app packages) then unpacking the tar will give the apk files. If the tar does not contain apk files then it does not. It's rather like a zip file. Windows Linux and Mac can unpack tar files. Try just double clicking the file in a file manager. Roger