Customizable Pomodoro Clock от ruuk

What is the Pomodoro Technique? https://en.wikipedia.org/wiki/Pomodoro_Technique

Features:
- Adjustable work and break streak times
- Customizable notification tone that plays at the end of each streak timer
- Customizable design colors to personalize your Pomodoro clock

This extension is open-source with an extension available on GitHub!
https://github.com/lukazio/pomodoro-clock-firefox

This extension is a derivative of https://github.com/macmorning/pomodoro-webext