Countdown Timer

How to use

1. Leave the Duration radio on to use Hours, Minutes, and Seconds. Those boxes start at 0, 5, and 0, so the display opens at 00:05:00.
2. Or select the Date and Time radio. It is a datetime-local field. Pick a local date and a clock time. The duration boxes hide while that radio is selected.
3. Click Start. The label becomes Pause. Pause freezes the remaining seconds, and Start continues them. A duration of zero seconds alerts you to set a duration greater than 0. An empty date alerts you to pick a date and time. A target in the past alerts that the target must be in the future.
4. Click Reset to stop the run and return the button to Start. In duration mode the display goes back to the numbers in the boxes. In date mode it goes back to 00:00:00.

When it helps

A quiz round, a stretch, or the time left until a departure you already know in local time. The display is hours, minutes, and seconds, and it steps once per second while running.

It is not a focus plan with a built-in break. The Pomodoro timer is locked to 25:00 of focus and 5:00 of break, and those lengths cannot be edited. If you would rather count up and mark splits, the stopwatch shows minutes, seconds, and centiseconds and can list laps.

Limits

The timer is a script in this tab. Close the tab, or let the browser discard it, and the countdown does not keep running. It will not finish in the background and it will not notify you later. There is no sound control on the page.

Date mode uses the local datetime field, not a zone picker, so the target is read in the zone this device is using. Pause does not save a named preset. Reset does not store the last run.