Open a timed link such as a 5-minute, 15-minute, or 25-minute timer and the countdown starts on its own. Stay with this stretch of work, and add a short note in the link if you want a message when time is up.

Share timing across the web when everyone should see the same clock. You do not need the extension to run a fullscreen online timer. ThisTask for Chrome and Edge is only for break reminders while you browse.