This countdown aims at a clock time or a calendar date instead of a duration. Choose a time today, such as 3:00 pm, or a date and time for something later. The target is written into the URL. A countdown to 3:00 pm is this page with ?at=15:00. Send that link and the other person sees the same target, interpreted in their own time zone as that clock time.
If the time you pick has already passed today, the countdown rolls to the next time that clock will strike. A date target does not roll. When that moment is in the past, the page says so. The digits use the same timestamp math as the other timers, so switching tabs does not eat seconds.
Use it for the end of a school day, a handoff at 3:00 pm, or a date you are willing to watch shrink. It is a bad tool for anything safety-critical. Space pauses the display updates only in the sense that you can leave the page. The target time does not pause. The world keeps moving toward 3:00 pm whether the tab is focused or not.
Questions
How do I count down to 3:00 pm?
Open the countdown to 3:00 pm, or set the time field to 15:00. If it is already past 3:00 pm, the timer targets 3:00 pm tomorrow.
Can I share a countdown?
Yes. The URL holds either at=HH:MM for a clock time or to=YYYY-MM-DDTHH:MM for a specific date and time.
Which time zone is used?
Your browser's local time. A shared at=15:00 link means 3:00 pm where the viewer is, not a single global instant.