Keyboard Test — Check Every Key Online

Press it, see it

Every key on your keyboard reports to the computer as a position code. Tap the tester above and press keys: the matching keycap lights amber while you hold it and stays shaded once released, so a quick sweep — left to right, row by row — proves every switch on the board. The readout line shows the four values developers care about (code, key, keyCode, which) plus which side of the board the event came from.

The counters up top do the diagnostic work: held now tracks simultaneous presses for rollover and ghosting checks, max rollover records the most keys your board managed to report at once, and keys tested counts how much of the layout you’ve verified. Hold a key past eight seconds and it gets flagged red as a possible stuck switch.

Three quick checks worth doing

• Dead-key sweep — press every key once. Anything that doesn’t shade in didn’t reach the browser. The dead-key checklist walks through the fixes from cheapest (reseat the USB plug) to real (replace the switch).
• Rollover probe — hold common gaming combos (W+A+Shift+Space, or four home-row keys) and compare what lights against what you pressed. What rollover and ghosting actually are explains 2KRO vs NKRO and why cheap matrices block certain triples.
• Feel test — if the board works but typing feels wrong, mechanical vs. membrane covers what the switch under each cap does to feel and sound.

On a laptop, run the same sweep when a key starts acting up — the laptop keyboard fix checklist orders the likely causes so you don’t open the chassis for a software problem.

Frequently asked questions

How do I test my keyboard?

Click or tap the on-screen keyboard once, then start pressing physical keys. Each key lights while held and stays shaded after release, so you can sweep every key row by row. The readout shows the exact code, key, keyCode and which values your browser received — useful when a key produces the wrong character or nothing at all. On a phone or tablet, tap the on-screen keys instead.

What does it mean if a key doesn't light up?

The key's signal isn't reaching the browser. Work through the dead-key checklist: rule out software (try another app, another OS profile, another port), then hardware (reseating the cable, cleaning under the cap). A key that fails in every app on every device is almost always a physical switch or matrix fault.

How do I test for ghosting and rollover?

Hold several keys at once — for example A+S+D+F, or Q+W+E — and watch which ones light. The held now counter and the held-keys strip show exactly what your computer received. If pressing three keys lights only two, that combination is blocked by your keyboard's matrix; if an extra key lights that you didn't press, that's ghosting. Rollover and ghosting explained has the details.

What is a 'stuck' key?

Any key held past the stuck threshold (8 seconds by default) is flagged red and a warning appears — the classic symptom of debris under a keycap or a failing switch registering without a press. Tap the flagged key a few times; if it stays held in the tester after you let go, the switch is physically stuck.

Does this work on a laptop or phone?

On a laptop, yes — press the built-in keyboard or an external one; both light the same on-screen keys (some laptop-specific Fn combos never reach the OS and can't be tested). On a phone, the on-screen keyboard is fully tappable so you can use it as a reference, but a mobile OS won't report a USB keyboard's raw codes — this tool is built for desktop keyboards.

Will this steal my browser shortcuts?

No. The tester only captures keys that would otherwise scroll the page or open browser UI — F-keys, arrows, Tab, Space — and only while the tester area is focused or your pointer is over it (the shortcut capture indicator shows when). Any Ctrl/⌘ combination is always passed through untouched.

What do 'code' and 'key' mean in the readout?

code is the physical position of the key (KeyA is always the key under your left pinky, whatever letter it prints), while key is the character it produced ('a', 'A', 'á' depending on layout and shift state). If a key lights but shows the wrong key value, your OS keyboard layout is mismatched — the hardware is fine.