Passata

Passata lets you concentrate on your work while still making yourself available to help your coworkers.  Unlike other "pomodoro" timers which focus on tracking your productivity, Passata is focused on protecting it.  Start the timer, and prop up your device where your coworkers can see it; it will display a "Do not disturb" message, along with the time until you are next available.  As the timer progresses, the display slowly turns from red to yellow; when it runs out, the display turns to green and an "Ask me anything" message is shown.  The timer and messages are customisable, and a variety of themes are provided.  A subtle sound plays when the timer runs out.

Passata includes a Today extension and an Apple Watch app.