Hourglass - Hourglass is the most advanced simple countdown timer for Windows.
Timetaco - Create your own countdowns, as easy as 3, 2, 1
AlarmDJ - Online Alarm Clock - Use YouTube videos or MP3 files as alarm sound. Works offline.
Coountdown - 3 2 1 ! Create day counter on menu bar macOS. 🚀
Free Alarm Clock - Free Alarm Clock is a free, full-featured and user-friendly computer alarm clock for Windows.
Padbury Clock Screensaver - Minimal screensaver for Mac