Keyboard tester

If a key never lights here, the signal is not reaching the browser at all. Try it in a text editor to confirm, then unplug and reconnect the keyboard, try a different USB port, and test on another computer if you can.

A single dead key on a mechanical keyboard is often a failed switch, which is replaceable. On a membrane or laptop keyboard it usually means debris under the key or a damaged membrane sheet, and a liquid spill is the usual cause.

Ghosting is when a keyboard stops registering additional keys because of how its switches are wired into a shared matrix. Press three keys in the wrong arrangement and the third simply never arrives.

N-key rollover means every key is read independently, so any number can register at once. Hold several keys here and watch the counter to see which kind you own. Six is a common limit on USB keyboards and is plenty for most use.

Chatter is a worn switch that sends two presses from one push. Press the suspect key slowly and deliberately about twenty times and watch the press counter for that key.

If the count climbs faster than you pressed, the switch is bouncing. On a hot-swappable keyboard you can replace the switch; otherwise some keyboards let you raise the debounce time in their configuration software.

Capture mode stops most keys reaching the browser, but a handful are reserved by the operating system and can never be intercepted by a web page. That is a security boundary rather than a limitation of this test.

Ctrl+W, Alt+Tab, Ctrl+Alt+Delete, Command+Q and the Windows key are the usual ones. Test those in your own operating system rather than in a browser tab.

The Fn key is handled inside the keyboard itself and never sends a key code to the computer, so no software on any platform can see it. It is not broken.

Media keys and brightness keys often go straight to the operating system too. If volume actually changes when you press them, they work, even though nothing lights up here.

Yes, and it works the same way. The layout drawn here is a full-size one, so a laptop without a number pad will simply leave that block unmarked, which is expected.

If several neighbouring keys are dead on a laptop, suspect the ribbon cable or a spill rather than individual switches.

code is the physical position on the keyboard and does not change with your language layout. key is the character that position currently produces, which does.

So on a French AZERTY layout the key next to Tab reports a code of KeyQ but a key of 'a'. keyCode is an older number that browsers still report for compatibility.

Only a physical one. On-screen touch keyboards send text rather than key events, so most of what this page measures does not apply to them.

A Bluetooth or USB keyboard attached to a phone or tablet does work, and reports the same codes it would on a desktop.

No. Key events are read, drawn on screen and discarded. Nothing is sent anywhere, nothing is stored, and reloading the page clears every mark.

For obvious reasons, do not type passwords into any keyboard test, here or anywhere else. Test with ordinary letters.

A key that fires continuously without being held usually has something physically holding the switch down: debris, a sticky spill, or a keycap fouling its housing. Pull the cap and check underneath.

If nothing is stuck, the switch has failed closed and needs replacing. In the meantime most operating systems let you remap the key to nothing so it stops interrupting you.