Timeful

Thanks to the Timeful app, you can regain more value, focus on your work, and stop unpleasant habits like constantly checking your smartphone.
The Timeful app starts a predefined timer (2 minutes - 2 hours) during which you will no longer use your smartphone. This allows you to fully concentrate on your work, your studies or whatever you want to do.
Once the timer has expired, the app will report back to you, and you can get a report of how much time you have been focused and what percentage you have kept up.
With the strict mode, you can also improve your behaviour even more by placing the smartphone face down. The smartphone must then be in this state for the entire duration.
The better the percentage, the better your productivity was.