Timers don't get any more minimal than this. Minimalist Timer is a super minimal timer which works beautifully well. You can turn the knob and set how long you will like the timer to run for. There are also 3 presets on the bottom left which you can adjust to your liking. Even when you leave the app, it'll continue to run in the background. Once the timer is up it'll alarm you and vibrate, according to the settings you input.