Question 1

How does the shared countdown work?

Accepted Answer

The link stores the absolute moment the timer ends, not the number of minutes left. Whoever opens it — now or in ten minutes, in another country — sees the correct remaining time, without any account or server syncing.

Question 2

Will the alarm sound if I switch tabs?

Accepted Answer

Yes, as long as the tab stays open. The countdown is based on the clock rather than a running counter, so background throttling cannot make it drift, and the page title shows the remaining time so you can see it from another tab.

Question 3

Does the timer keep running if I reload the page?

Accepted Answer

A shared countdown does, because the end time lives in the link. A stopwatch does not — reloading starts it from zero.