Om Time

This is a simple and free meditation timer. You will hear one ring in the beginning, one at one third of the duration, one at two thirds of the duration, and finally three rings at the end. Sound recorded from a real singing bowl (displayed in the background).

You can customize the timer to 6, 15, 30 or 60 minutes.

Free and open source. Code available at https://github.com/bani/omtime

No tracking, no ads, and no special permissions other than changing your media volume (which is set to maximum while the app is visible unless settings are changed).