An egg timer
This page starts counting 6 minutes the moment it opens, and makes a sound when it finishes. Nothing to set, and nothing to press first.
What people set 6 minutes for
Six minutes from boiling for a set white and a soft yolk, straight from the fridge into already-boiling water.
Worth knowing
Egg timing is really water timing: start counting when the water returns to a boil, not when the egg goes in, or every egg is undercooked by the same minute.
Questions
Do the timers keep running if I switch tabs?
Yes. The countdown is measured against a monotonic clock rather than counted in ticks, so a backgrounded tab, a throttled timer or a laptop lid closing does not lose time — when you come back it shows what it should, not what it managed to count.
Does a timer survive a daylight-saving change?
Yes, and the distinction matters. A countdown measures elapsed real time, so a timer set for six hours across a spring-forward still runs six real hours even though the wall clock advances seven. An alarm set for a wall-clock time does the opposite: it fires when the clock says so, which is what you want from an alarm.