Boxodoro is a simple timer for the Pomodoro technique of working 25 minutes followed by a 5-minute break.
It starts automatically and snaps to the hour. The alarm sounds at 5 minutes, 30 minutes, 55 minutes, and the end of every hour. This is useful for adhering to a schedule (such as when timeboxing) as you'll never have a Pomodoro run into the next block of time.
Chime sound comes from SoundBible and this project makes use of the react-countdown-now and buzz packages.