About Countdown Timer
Run multiple simultaneous countdown timers with 100ms refresh accuracy. Set timers to a specific date and time, or use quick presets for 5, 10, 15, 30, or 60 minutes. Each timer supports pause/resume, browser notifications, and sound alerts using an inline base64 WAV tone.
- Multiple concurrent timers, each with independent pause/resume state
- Quick preset buttons create instant timers for 5, 10, 15, 30, and 60 minutes
- Custom timers accept any future date and optional time
- Browser Notification API integration for timer completion alerts
- Sound alerts use an embedded base64 WAV tone—no external audio files
- Visual states: active (blue), paused (yellow), expired (red)
Frequently Asked Questions
- Will timers keep running if I close the tab?
- No. The countdown runs in a JavaScript interval that stops when the tab closes. If you need persistent timers, keep the tab open. Browser notifications will fire even if the tab is in the background, as long as it’s still loaded.
- How accurate is the timing?
- The interval refreshes every 100ms and compares against the system clock, so displayed time is accurate to within a fraction of a second. It’s not suitable for precision timing applications, but it’s more than adequate for everyday countdowns.