Cloud backup storage service for android app

[WonderSoftwares via StackOverflow]

I am developing Android Gallery app which has online backup storage for each users so that they can upload their files to their cloud space to avail these features listed below.

1. Can have more free space on mobile by uploading files to cloud.
2. Easily download their files back to phone in case factory reset phone or lost phone using their id and password or google authentication.
3. (optional)users can increase their space volume by purchasing in-apps.

Tried uploading files to google drive but files are publicly visible in google drive.

I have seen so much application in play store using own cloud services(QuickPic, G Cloud, G Lock, KeepSafe) but I can not find any similar example yet. Thank you in advance.

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