I was doing some research yesterday for the best exercise interval timer app and settled for this one. It offers endless possibilities for customisation, and the UI is nice. I am still experimenting with it, and already consider purchasing a license.

Here's one of my custom workouts, why don't you give it a try and send some feedback?

https://exercisetimer.net/workouts/shared/hcfq3i89jwv97bgw0o