What modes does the clock have?

Three: Clock (the current time, with optional 12/24-hour toggle and seconds), Stopwatch (start/stop/lap with millisecond precision), and Timer (countdown with chime alert and Pomodoro presets).

Does the alarm go off if my screen is locked?

On most platforms the chime will play if the tab is in the background, but a fully-locked phone may suppress it. For reliable alarms with the device locked, the OS-level Clock app is more reliable.

What is the Pomodoro timer?

Pomodoro is a time-management technique: 25-minute focused work blocks separated by 5-minute breaks. The clock has it built in as a one-click preset.

Are saved laps persistent?

The current stopwatch session (running time + laps) survives reloads via localStorage. Closing and reopening the tab continues the timer.

Clock — Stopwatch, Timer & World Clocks

00:00:00

World Clocks

Stopwatch

00 : 00 . 00

Start the stopwatch to track laps.

Timer

hr

min

sec