Keyboard Tester

Press any key. It lights up blue while held and turns green once it has been tested.

–Last key

–event.code

–keyCode

0Held now

0Max at once

0Keys tested

How to test your keyboard

Click anywhere on this page and start pressing keys.
Each key you press on the layout above turns green. Any key that never lights up may be dead or blocked.
Hold several keys at once to see how many your keyboard can register together (key rollover).

What do the numbers mean?

event.code is the physical key position (for example KeyA), the same on every layout. keyCode is the older numeric code. “Max at once” shows the highest number of keys held at the same moment — useful for spotting ghosting on budget keyboards.

FAQ

A key does not light up. Is it broken?

Try pressing it a few times and a bit harder. If it still does not register, clean under the key, test with another browser, and check whether the operating system catches it (some media or Fn keys are handled by the system before the browser sees them).

Why do Fn, Windows or Print Screen not work?

Browsers cannot see some keys, because the operating system or keyboard firmware handles them first. That does not mean they are broken.

What is ghosting?

Ghosting is when pressing several keys at once makes a key not register, or registers a key you did not press. Hold combinations you use (for example gaming keys) and watch “Max at once”.

Is my typing recorded?

No. Key presses are only displayed on this page and are never sent anywhere.

Running a full keyboard check

Click on the page once so it has focus, then press keys. A key turns blue while it is held and stays green afterwards, so you can see at a glance which ones you have not yet touched.
Work through the picture row by row, from Esc along the top to the arrow keys at the bottom right. Press each key once and release it.
Watch the counter named "Keys tested". The drawn layout contains 87 keys, so a counter of 87 with every key green means nothing was missed. Press "Reset" to clear everything and test again.

Alt+Tab, the Windows key and similar shortcuts may move you out of the page before it can register them. The held-keys list is cleared whenever the browser window loses focus, so a key you were pressing when that happened will not be stuck on screen.

Reading the six numbers

Last key is the value of the key event. It depends on your layout and on Shift: pressing the key beside Tab shows "q" or "Q" depending on Shift, and on a French layout the same physical key gives "a".
event.code names the physical location, independent of layout. KeyQ is always the key to the right of Tab, whatever is printed on it. This is the value the coloured board follows.
keyCode is an older numeric code. Browsers still report it, but it is deprecated, and programmers are advised to use the code and key values instead. It is shown because many older scripts and games still depend on it.
Held now counts the keys currently down. Max at once remembers the highest number reached since the last reset.

Holding a key down makes the operating system send repeated press events, but the tester stores keys by name, so a repeating key still counts as one held key.

Testing rollover and ghosting

Keyboards report presses through a wiring grid called a matrix. On cheap models, certain combinations of three or more keys cannot be told apart electrically, so a key goes missing or a phantom one appears. This is ghosting. Rollover describes how many simultaneous keys are reported correctly.

To test it, press and hold keys one at a time and watch "Held now". Try the combination that matters to you, for example W, A and Space plus Shift for a game, or hold six letter keys and then add a seventh. A keyboard limited to six ordinary keys, which is a common limit for standard USB reports, will stop counting once you pass six non-modifier keys; modifiers such as Shift and Ctrl are reported separately and do not use up those slots. Gaming boards advertise "N-key rollover" and should keep counting as you add fingers, as far as your hands allow. Results can also differ between wired and wireless modes and between operating systems.

Diagnosing a key that does nothing

Press it several times, including slowly and firmly, to separate a worn contact from a one-off miss.
Try the key in a different program, such as a plain text editor. If it works there but not here, the browser cannot see it.
Try another USB port, or another computer. A key that fails everywhere points to the keyboard; a key that works elsewhere points to software or a driver.
If a key types twice or sticks, tap it repeatedly and watch whether the "Held now" count stays above zero after you let go. Crumbs and spilled drinks are the usual cause.
Check whether Fn or a gaming-mode switch changes the result. Some boards disable the Windows key or remap the function row on purpose.

What this tester cannot show

The picture is a full-size layout without the numeric keypad. Keypad keys still register and appear in "Last key", "event.code" and the "Keys tested" count, which means that count can exceed 87, but they have no square to light up.
Some keys, such as Fn, volume and brightness keys, and often Print Screen, are handled by the operating system or keyboard firmware before the browser receives anything.
Most key presses are blocked from triggering browser actions while you are testing, so the page does not scroll or open menus. Combinations that hold Ctrl or Command with another key are let through so that normal browser shortcuts keep working.
The layout shown is a US-style one. Other layouts have a different arrangement of keys near Enter and the left Shift key; the physical keys still register under their codes.