Keyboard Tester — Check Every Key Online

How to use

1. Focus the page. Click anywhere on the page so it receives keyboard input, then start pressing keys.
2. Press every key. Work across the whole keyboard. Each key turns green while held and stays marked as tested after release.
3. Check for problems. A key that never lights up is dead, one that stays green is stuck, and keys that drop out during chords reveal ghosting.

Why test this

Keyboard faults tend to be intermittent and specific, which makes them maddening to pin down in normal typing: a key that misses one press in twenty, a switch that occasionally chatters, or a combination that silently drops a keystroke mid-game. Mapping every key to a live on-screen layout turns that vague suspicion into something you can see. Run it before buying a used keyboard, after cleaning or a spill, when a game keeps ignoring a movement key, or to confirm a new board registers everything before the return window closes. The test also exposes ghosting and rollover limits, which matter for gaming. Cheaper membrane boards can fail to report several simultaneous presses, so a crouch-jump-strafe combo loses an input at the worst moment. Seeing exactly which keys and which combinations fail tells you whether to clean a switch, claim a warranty, or rebind around a hardware limit.

What the results mean

Each key on the diagram lights green the moment you press it and stays marked as tested after you let go, so a clean board fills in completely as you work across it. A key that never lights when you press it is dead (it is not reaching the browser at all), while a key that stays green after release is stuck on. To test rollover and ghosting, hold several keys at once and watch the diagram: if a key you are pressing fails to light while others are held, that combination is ghosting, a limit of the keyboard's matrix rather than a broken switch. Matching is by physical position, so on a non-US layout the highlighted key may not match the printed legend even though the position is right. A few keys (typically F5, F11, and F12) are reserved by the browser and may never register. That is a browser restriction, not a fault in your keyboard.

FAQ

How do I test for a dead key?

Press it and watch the on-screen key. If it never lights up, the key is not registering. That's a dead key, as long as the browser isn't reserving it.

What is key ghosting and how do I test it?

Ghosting is when a keyboard can't report several keys pressed at once. Hold three or four keys together. If one stops registering, that combination ghosts.

Why don't F5, F11, or F12 register?

Browsers reserve some keys for refresh, full screen, and dev tools, so they may not reach the page. That's a browser limit, not a fault in your keyboard.

Why does the wrong key light up?

The tester matches by physical key position (event.code), so a non-US layout can map differently. The position is correct even if the printed legend differs.

Is this keyboard tester free?

Yes. It runs entirely in your browser, needs no installation, and stores nothing.

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