Reflex measures your reaction time — wait for the screen to turn green, then tap as fast as you can. It takes five goes and shows your average in milliseconds. A fun way to test how quick you are (and to challenge a friend). Nothing is uploaded.

Tap to start

Wait for green, then tap as fast as you can

Reaction time is measured from the moment the screen turns green to your tap, using a high-resolution clock. Typical visual reaction times are around 200–300 milliseconds. If you tap before it turns green, that round is a false start and doesn't count. Everything runs on your device.