How to use the keyboard tester
- Choose your keyboard under Keyboard layout: ANSI (US) has a wide one-row Enter key and a long left Shift; ISO (UK / EU) has a tall Enter key and an extra key between the left Shift and Z; Mac shows the control, option (⌥) and command (⌘) keys. Switch Numpad off for a tenkeyless or laptop keyboard.
- Click the keyboard picture where it says Click here to start testing. The badge next to the title changes to Testing and the frame turns green.
- Press every key once. A key turns blue while it is held and stays green once it has worked. The counter shows how many keys of the chosen layout have been tested, for example "87 of 104 keys tested".
- Look for keys that stay white after you press them (dead keys), keys that stay blue after you let go (stuck keys) and keys outlined in red (chatter, which types double letters).
- To test ghosting and rollover, hold several keys at once and watch Rollover and ghosting: every key you hold should appear there, and most keys at once records your best combination.
- Hold Esc for a second or click outside the keyboard to stop. Reset clears everything and starts again.
What the key codes mean
Every key press produces a keydown event and every release a keyup event, and the Last key event panel shows what the browser reports:
| Field | Meaning | Example |
|---|---|---|
key | The character or action the key produces with your current language layout and modifiers. | a, A, Enter |
code | The physical key position, independent of language. The tester uses this to light up the right key. | KeyA, ShiftLeft |
keyCode | The old numeric code still used by many games and older scripts. It is deprecated but widely supported. | 65, 13 |
| Location | Tells left and right modifiers and numpad keys apart. | Left, Right, Numpad |
| Auto-repeat | "Yes" while a held key is repeating, as when you hold a letter down in a text box. | Yes / No |
On a French AZERTY or German QWERTZ keyboard, the key labelled A on a US keyboard still reports KeyQ or KeyA by position. In Chrome and Edge the tester reads your system layout and relabels the letter and symbol keys to match, so you see the characters printed on your own keys.
Keys a browser cannot detect
A web page only sees keys that the operating system and browser pass on, so a few keys can never light up here, and that does not mean they are broken:
- Fn is handled inside the keyboard itself and never reaches the computer as a key press. Test it by combining it with the key it changes, such as Fn + F2.
- Media, brightness and volume keys are usually handled by the operating system. Some appear under Other keys detected; many do not.
- System shortcuts such as Alt + Tab, Windows + L, Ctrl + Alt + Delete, Cmd + Tab, Cmd + Space and Cmd + Q act before the browser sees them.
- Print Screen on Windows often sends only a key release; the tester counts that as a press. On some laptops it opens the snipping tool instead.
- On a Mac, Caps Lock reports only one event per switch on or off, and keys released while Cmd is held may not report their release, so the tester clears held keys when Cmd is let go.
Ghosting and key rollover explained
Key rollover is how many keys a keyboard can report at the same time. Ghosting is when a combination makes a key you did not press appear, and blocking (often loosely called ghosting too) is when one of the keys you held is ignored. Cheaper keyboards share wires between keys in a matrix, so some three- or four-key combinations fail; many gaming keyboards add diodes or anti-ghosting to avoid it. Keyboards labelled NKRO (n-key rollover) can report every key at once over a suitable connection, while the traditional USB boot protocol is limited to six normal keys plus the modifiers (often called 6KRO).
The result also depends on the operating system and browser, so test the combinations you actually use in games or shortcuts rather than chasing the highest count.
Troubleshooting dead, stuck or repeating keys
- Key does not light up: try it on another computer. If it fails everywhere, the switch or its connection is faulty. Several dead keys in one area often point to a liquid spill or a damaged laptop ribbon cable.
- Key is sticky or types twice: turn the keyboard upside down and gently tap it, then use compressed air around the key. On mechanical keyboards, remove the keycap and blow out the switch. Chatter that comes back usually needs a new switch.
- Keys respond slowly or need a long press: on Windows, open Settings, Accessibility, Keyboard and turn off Filter Keys. Sticky Keys makes Shift, Ctrl and Alt stay on after one press, which looks like a stuck modifier.
- Wrong characters appear: the physical key works but the language layout is different. Check the input language in your system settings, or the shortcut that switches layouts, such as Alt + Shift or Windows + Space.
- Wireless keyboard: charge or replace the batteries, move the receiver closer and re-pair it. If a laptop's own keyboard fails but an external one works, the built-in keyboard or its cable is at fault.
Testing a new setup? Check your pointer with the mouse test for buttons, double clicks and polling rate, measure how fast you type with the typing speed test, or try the gamepad tester for controllers. All of them are on the device tests page.
Privacy: the tester runs entirely in your browser and does not record or send what you type. Only your layout choice and numpad setting are saved in this browser's local storage.
Frequently asked questions
How do I test my keyboard online?
Open this page, click the keyboard picture to start, and press every key. Each key that works turns green and the counter shows how many keys have been tested. Keys that stay white after pressing are not reaching the computer.
Why does a key not light up even though it works?
Some keys never reach a web page: Fn, many media keys and system shortcuts such as Alt + Tab or Cmd + Tab are handled by the keyboard or the operating system first. If the key works in other programs, it is fine.
How can I check for keyboard ghosting?
Hold the key combination you care about, for example W, A, Shift and Space for a game, and check that every key appears under Rollover and ghosting. If one of them is missing, or a key you did not press lights up, your keyboard cannot handle that combination.
Why does my keyboard type double letters?
That is usually key chatter: a worn or dirty switch makes contact twice in one press. The tester flags a key in red when it registers two presses within 30 ms. Cleaning can help; a mechanical switch that keeps chattering normally has to be replaced.
Why does Ctrl light up when I press Alt Gr?
On Windows, the Alt Gr key on many European keyboards is sent as Ctrl + Alt, so the left Ctrl key lights up as well. This is normal behaviour, not a fault.
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