DateMath Pro
Date calculations for ranges, business days, and recurrences
countdownpro.app
Countdown timer with alarms, presets, and shareable links
Free countdown timer with browser push notifications, presets for cooking and interval workouts, shareable timer links, and unlimited simultaneous timers. Timers persist across reloads and work offline once loaded.
People timing tasks and workouts.
CountdownPro is an independent website. Tools Lib lists it; features and pricing are set by its makers and can change.