Countdown Timer, Stopwatch and Pomodoro: Why a Background Tab Does Not Make Time Drift

A timer that counts one second at a time drifts when the browser slows a tab you are not looking at. This tool avoids that by calculating from a stored end time.

Why it does not drift

The time remaining is calculated from a stored finish time, not counted second by second. Even if the tab is slowed, the number is right when you come back.

Three tools

• A countdown with an alarm, typed as 25, 1:30:00 or 2m 30s.
• A stopwatch with lap times.
• A Pomodoro of 25 minutes of work and 5 minutes of rest.

Helpful features

• The time shows in the tab title.
• It can keep the screen awake.
• Once loaded it needs no internet connection.

About the alarm

For the sound to play, keep this page open in a tab. Some browsers limit sound from tabs you are not looking at.