Keyboard test

Press every key on your physical keyboard, one at a time. Each key lights up here as you press it and stays marked once you have tried it. Switch to the Rollover tab to hold several keys at once, and the History tab to see every key press in order.

It listens for the codes your keyboard sends the browser and reports three things: keys that chatter (fire twice from one press), keys that never register at all, and how many keys you can hold down at once before the keyboard stops adding more (rollover).

Chatter is a single key press that the keyboard reports as two or more presses in quick succession, usually from a worn switch. This test flags any key that re-presses within 30 ms of its own release.

Rollover is how many keys a keyboard can register at the same time. Most keyboards manage at least 6; below that, holding more keys just stops adding new ones, and the test tells you where yours stops.

The physical position and code of some keys, such as the key next to Enter or the key next to left Shift, differs by layout. Matching the layout to your keyboard makes sure the diagram lines up with the key you actually pressed.