Do you want sell your old phone? give it to a friend? afraid of restoring your photos and videos?? factory reset is not enough because some programs can restore the data even if you restored your phone to factory reset.
ZeroFill is the solution, Just delete all your data then install the Application and start filling your empty space with random data.
I advise you to repeat this action at least 3 times and change the filling method every time and you now know for sure that no one will be able to restore.
It's an Open Source Project and you can find the code on Github : https://github.com/Morxander/ZeroFill
