Keyboard tester: test every key online
Press Start testing, then press each key. The keyboard below lights up as keys register, so you can find a dead key, a sticky key or a rollover limit in under a minute. Nothing is sent anywhere.
How the keyboard test works
Every key on your keyboard sends a signal called a scan code when it is pressed, and the browser turns that into a key event the page can read. This tester listens for those events and lights the matching key on the on-screen layout. A key that stays dark after you press it did not reach the page, which points to a dead switch, dirt under the keycap, a broken trace or a key the system keeps for itself.
Keys turn green after you have pressed them once and bright green while you hold them, so you can work along each row and see what is left. The panel on the right counts how many keys you have covered and lists the ones you have not pressed yet, which makes a full check of a standard layout quick.
What the results mean
A quick guide to reading the tester. Compare your keyboard against these common cases.
| What you see | Likely cause | What to try |
|---|---|---|
| One key never lights | Dead switch or debris | Clean it, then replace the switch or keyboard |
| A key lights twice per press | Chatter from a worn switch | Clean it or swap the switch |
| Extra keys light when you hold several | Ghosting on a membrane board | Use a keyboard with N-key rollover |
| Fn and media keys do nothing | Handled by the keyboard itself | Normal, not a fault |
Key rollover and ghosting explained
Rollover is how many keys a keyboard can report at the same time. Cheap membrane keyboards often share wiring between keys, so pressing three or four at once can make another key appear or a real one vanish. That is called ghosting, and it is why some games miss an input when you run, jump and shoot together. Many mechanical keyboards report every key independently, which gamers call N-key rollover.
Hold down as many keys as you can and watch the number labelled most at once. If it stops at a small number while your fingers are clearly down, your keyboard is limiting you. Some keyboards also limit keys by region, so test the movement keys with a few others and try again.
Fixing a key that does not register
Start with the simple things. Unplug and replug the keyboard, try another port, and test with another computer to rule out the software. Turn the keyboard upside down and tap it gently to clear crumbs, then use compressed air under the keycap. A key that registers twice or keeps repeating can have a worn switch, and on many mechanical boards the switch can be swapped without a soldering iron.
If only a few keys fail on a laptop, check for a liquid spill and look for a keyboard cable that has worked loose. For a keyboard under warranty, a short test result like the one here makes a clear case for the seller. Once the keys are sorted, try the typing speed test or the mouse tester.
How to use the keyboard tester
- Click Start testing so the page captures your keys.
- Press each key in turn and watch it light on the on-screen keyboard.
- Hold several keys together to find your rollover limit.
- Check the list of keys you have not pressed and test those.
- Press Reset to run again or Stop testing to leave test mode.
Common mistakes to avoid
- Forgetting to start the test, so key presses go to other shortcuts.
- Treating Fn and media keys as faulty when the keyboard handles them itself.
- Judging rollover while the keyboard is on a wireless connection that limits report size.
Related tools and guides
Keep going with these: Gamepad tester, Typing speed test, Mouse tester, reaction time test, best graphics cards guide.
Frequently asked questions
How do I test if my keyboard keys work?
Open this page, click Start testing and press every key. Each one lights up on the on-screen keyboard when it registers. Keys that stay dark after you press them are not reaching the browser, so clean them or try another keyboard.
What is key rollover?
Rollover is the number of keys a keyboard can register at the same moment. Basic keyboards may handle only a handful, while many mechanical ones report every key at once. Hold keys down here and the tester shows the most it saw together.
Why does my keyboard type the wrong letters?
Common causes are the wrong keyboard language layout in the system settings, stuck keys, ghosting on a cheap board or a loose cable. Test with this tool, check the layout in system settings, and try the keyboard on another computer to find the cause.
Why do the Fn keys not light up?
Fn, volume, brightness and many media keys are processed inside the keyboard or the operating system and never reach web pages. That is normal. Test them by using their function directly, such as changing volume or screen brightness. Check them by using the function itself.
Is this keyboard test safe and private?
Yes. The test runs entirely in your browser, nothing you type is stored or sent, and the page ignores what the keys spell. It only marks which keys were pressed. Close the page and the results disappear completely. Nothing is recorded or uploaded at any point.
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