A free program for Android, by Viko Co..

Interval Trainer PRO for Crossfit, HIIT and other types of interval training is an easy-to-use, fully personal timer that allows you to choose from different exercise types, adjust round length and rest time, count rounds, bell sounds and alerts, and visualize your progress.

The app is ideal for workouts using heavy bags, jump ropes, push-ups, pull-ups, double-end bags, or other types of interval training at the gym or home.

This app is useful for athletes looking to increase their endurance, strength, and muscle tone through high-intensity interval training (HIIT). It provides a great workout that helps to improve your physical fitness and health.