TomatoTomato от Kylemrtnz, Eric Gilligan

Tomato Tomato is a minimalistic productivity/work-flow management extension. Its concept revolves around working for a set amount of time, then taking a short break before working again. At the end of 4 work/break cycles, a longer break is taken. While the work session is active, Tomato Tomato blocks websites which you do not want to visit in order to keep you focused.

Key Features:
- Customize the timer lengths (work/break/longbreak)
- Customizable list of blocked websites
- Notification upon cycle completion

Pomodoro™/Focus Timer extension for Mozilla. The Pomodoro Technique® and Pomodoro™ are registered trademarks of Francesco Cirillo