How to run the countdown
- Set the time. Tap a preset, or type hours, minutes and seconds. Presets start straight away; typed times wait for Start.
- Choose the alarm. Pick a sound, how long it rings and the volume, then press Test sound so you know it can be heard.
- Launch. Press Start or the space bar. Pause and resume as often as you like, add a minute with +, or go fullscreen for a classroom, kitchen or stage.
The timer does not count down by adding up ticks, which browsers slow down in hidden tabs. It notes the moment the countdown will reach zero and compares that with the clock on every redraw, so the display is right the instant you come back. The alarm is handed to the browser's audio system in advance, so it sounds on time even while you work in another tab. The remaining time also shows in the tab title.
Your last time, label and alarm settings are remembered on this device. A running countdown survives a page reload, too.