How to Test Every Key on Your Keyboard

A visual keyboard tester highlights each key as it registers and keeps tested keys marked, so coverage is obvious at a glance. Sweep row by row — including the ones you never think about, like Scroll Lock, Pause, and the numpad — until every key on the visual board is marked.

Intermittent keys are the sneaky failures: they work most presses and drop some. For any suspect key, press it twenty times in a row and confirm every press registers.

The operating system intercepts a few keys before the browser sees them: Fn (handled inside the keyboard itself), some Windows/Command combinations, and certain media keys. If one of those doesn't light up, it isn't evidence of a broken key. Everything else — letters, numbers, modifiers, arrows, function keys — should register.

The tester displays three values developers care about: key is the character or action the press produces ('a', 'Enter'); code is the physical key position ('KeyA'), which ignores layout; and keyCode is the deprecated numeric identifier older code still uses. If you're wiring keyboard shortcuts, prefer code for position-based controls (like WASD) and key for character-based ones.