Is my clock right?

Keep this tab in front. In a background tab the browser slows timers down (Chrome to once a second, later to once a minute; phones may pause the page). TimeBench counts time from the clock, not by ticks, so the stopwatch and timer never lose time, and the timer’s alarm is scheduled on the audio clock. But the screen updates and vibration wait until you come back, and on phones the alarm only sounds while the page is open.