100 Hours Timer
Press Space to start/pause, R to reset, F for fullscreen, ? for help.
100:00:00
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About 100 Hours Timer
Set a 100 Hours countdown timer for free. This online timer works offline as a PWA, supports audio alerts, keyboard shortcuts, and repeat mode.
How to use
Click the Start button to begin the countdown. Use +1m/−1m buttons to adjust time quickly, or click the timer display to set a custom duration. Press Space to pause/resume, R to reset, and F for fullscreen.
Features
- Works completely offline after first load (PWA)
- Multiple timers (add with the + button)
- Fullscreen mode for presentations and classrooms
- Repeat mode for continuous intervals
- Browser notifications (with permission)
Use cases for 100 Hours
- Full work day
- Overnight timers
- Server maintenance windows
- Hackathons
- Exam supervision
Tips for using this timer
- Press Space to start/pause
- Press R to reset timer
- Press F for fullscreen mode
- Click the + button to add multiple timers
- Enable Repeat mode for continuous intervals