How to mix / overlay two mp3 audio file into one mp3 file (not concatenate)

Question

I want to merge two mp3 files into one mp3 file.for example if 1st file is 1min and 2nd file is 30 sec then the output should be one min. In that one min it should play both

Answer 1

I am not sure if you want to do it on an Android phone (looks like that because of your tags), but if I'm right maybe try LoopStack, it's a mobile DAW (did not try it myself).

If you are just "mixing" two files without adjusting the output volume your output might clip. However I am not sure if it's possible to "mix" two mp3 files without decoding them.

If it is okay for you to merge them on your PC try Audacity, it's a free desktop DAW.