TopitApp

The idea behind TopitApp is very simple. You use the app to gather a form of internal currency named credits from various sources, like ads or installing apps on your phone. When you get enough credits from these actions, you can turn them into money and recharge your phone.
 
The application is really simple to use, but it takes quite a long time to get enough credits to matter. From time to time, some of the offers will be much higher than usual, but that’s pretty much it.
 
TopitApp is not available in all regions, so your shouldn’t be surprised if you don’t find it in the official store.