MacMenuBar - A curated directory of 200+ Mac menu bar apps
Hourglass - Hourglass is the most advanced simple countdown timer for Windows.
Gestimer - For those little reminders during the day
Free Countdown Timer - Free Countdown Timer is a free, full-featured and user-friendly countdown timer for Windows
Spaceman - A macOS app to view virtual desktops in the menu bar
SnapTimer - SnapTimer is a simple, free, portable countdown timer for Windows.