Keyboard Tester

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 you release it.
3. Check for problems. A key that never lights up is dead, one that stays green is stuck, and keys that drop out during a chord reveal ghosting.

Why test this

Keyboard faults are usually intermittent and specific, which makes them maddening to pin down in normal typing. One key misses a press in twenty. A switch chatters and fires twice. A combination silently drops an input 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 a 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 most for gaming. Cheaper membrane boards often can't report several simultaneous presses, so a crouch-jump-strafe combo loses an input at the worst moment. Once you see which keys and combinations fail, you know whether to clean a switch, claim the warranty, or rebind around a hardware limit.

What the results mean

Each key lights green the instant you press it and stays marked after you let go. A healthy board fills in completely as you work across it. A key that never lights when pressed is dead. It's not reaching the browser at all. One that stays green after you release it is stuck on. To check rollover and ghosting, hold several keys at once and watch the diagram. If a key you're holding drops off while the others stay lit, that's 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. F5, F11, and F12 are reserved by the browser and won't register. That's a browser restriction, not a keyboard fault.

FAQ

How do I test for a dead key?

Press it and watch the matching key on screen. If it never lights up, it's not reaching the browser. That's a dead key, unless it's one the browser reserves, like F5 or F12.

Why does a key register twice when I press it once?

That's chatter, usually from worn or dirty switch contacts that bounce and fire a second signal. You'll notice it as a doubled letter when you type normally. Cleaning or swapping the switch fixes it.

What is key ghosting and how do I test it?

Ghosting is when a keyboard can't report several keys held at once. Hold three or four together, like W, A, and Shift. If one stops lighting up while the others stay green, that combination ghosts.

How many keys can I hold at once?

It depends on the board. Many keyboards over USB report up to six keys plus modifiers (6-key rollover), the default HID limit. Boards with N-key rollover register every key. Hold a handful and count how many stay green.

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

Browsers reserve some keys for refresh, full screen, and dev tools, so they don't 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 in your browser with no software to install. There's no account, no upload, and it works with any keyboard, any brand.

Embed the keyboard tester on your page

Covering a keyboard review or a build guide? Add the keyboard tester so readers check every key for dead presses and ghosting on the spot. One snippet, no install, and a test takes under a minute.

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