Actuflow - App for checking why you use your smartphone before using it
Hourglass - Hourglass is the most advanced simple countdown timer for Windows.
RescueTime - Time management software that shows you how you spend your time & provides tools to help you be more productive.
wnr - Better than pomodoro, this timer app balances work and rest.
DND Me - Schedule Do Not Disturb from your Mac's menu bar
Free Countdown Timer - Free Countdown Timer is a free, full-featured and user-friendly countdown timer for Windows