APK task

Hi all, could somebody suggest me an open source tool to edit APKs other than the only and buggy one offered I the play store?
Thanks in advance and greetings

It’s not allowed to change the code of someone if the code is not open source.
More over you should provide your modifications if the code is open source.

I’m afraid there’s some kind of mistake.
The task I mean to carry out is referred to APK’s running in my own device and concerns modifications such as change beauty and remove unwanted permissions, functions that the app ''APKeditor"" offered in the play store provides without any warning about allowances or restrictions . It also provides an user guide and string, resource, manifest tabs and tools to change contents at user’s discretion. Unfortunately it’s tremendously buggy.
Is my query more understandable now ?
Thanks for your answer.

Try Xposed for that.