Keyboard Tester — Check Keys, Chatter and Rollover
Press any key and see it light up on the on-screen keyboard. Keys you have pressed turn green, keys held down turn cyan, and a key that fires again within a few milliseconds (chatter) turns yellow with the interval shown. Hold several keys at once to find out how many your keyboard registers simultaneously. Detection uses the physical event.code value, so the result is the same whatever input language or layout you use. Key history stays on this screen only and is never saved or transmitted.
Keyboard Input Test
Press keys and watch them mirror onto the layout below. Spot keys that never register, keys that fire multiple times from one press (chatter), and your simultaneous-input limit. Keys you press are not stored.
0Keys seen
0Total presses
0Max simultaneous
0Possible chatter
Last input
- event.code
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- event.key
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- keyCode
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- Modifiers
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- Since last
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Input order Last 40
No input yet. Press any key to begin.
FAQ
I pressed a key and nothing happened
While this page is open it always listens for keys — there's nothing to turn on. If one key still doesn't respond, it really isn't being detected — except that the Fn key, dedicated laptop keys (brightness, volume) and shortcuts the operating system grabs first (Win+L, Alt+Tab, etc.) never reach the browser, so this tool can't check them. Tab lights up, but its default browser behaviour (moving focus) is deliberately left alone so you can still leave the page.
How is chatter (one press, several inputs) detected?
A key is flagged when it is re-pressed within 30 ms of release — a person can hardly press the same key twice that fast on purpose. It turns yellow and shows the interval. Repeats the operating system generates while you hold a key (Auto-repeat) aren't chatter and aren't counted. One or two flags may be false alarms — watch whether the same key keeps getting flagged.
How do I check N-key rollover?
Hold several keys down at once and the Max simultaneous value climbs. Cheap membrane keyboards top out at 3–4 keys, while gaming keyboards register 6 or more, or every key. However, Ctrl, Alt and Shift combos can clash with browser shortcuts, and this tool deliberately doesn't block them, so testing with letter keys is more accurate.
Does it work the same in other input languages?
Yes. Rather than the typed character, this tool uses the Physical key (event.code) value, so the same key lights up whatever your input language or keyboard layout. Note that the Korean/English toggle key to the right of the bottom-left Alt key arrives, depending on the device, as
AltRight or a separate code.
Where are my keystrokes stored?
They aren't stored. Stats and input order live only in this page's memory and vanish on refresh. Nothing goes to browser storage or a server — the key sequence could contain passwords, so there's no reason to keep it.