Hourglass - Hourglass is the most advanced simple countdown timer for Windows.
Time 2 - Stay focused and crush procrastination
wnr - Better than pomodoro, this timer app balances work and rest.
Progress Bar OSX - This is your life and it's ending ⏳ one minute at a time
Free Countdown Timer - Free Countdown Timer is a free, full-featured and user-friendly countdown timer for Windows
Gone - An ephemeral to-do list