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Keyboard Tester

Press Start testing, then press every key. Each key lights up on the on-screen keyboard and stays marked once it works. Keys that never light up are faulty or blocked by your system. Press Esc to stop.

Keyboard Tester

Not testing. Keys work normally on the page.

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Keys light up while held and stay shaded once tested; a dashed outline means the key chattered. Fn and some system keys (like the Windows key combos and media keys) never reach the browser, so they can't be tested here.

A key doesn't work, or types twice?

Key does nothing

  1. Test it in another app, such as a text editor. If it works there, a shortcut or app setting is taking the key.
  2. Unplug the keyboard and plug it into another USB port, straight into the computer rather than a hub.
  3. For wireless keyboards, charge or replace the battery, move the receiver closer and pair it again.
  4. Check that Fn Lock, Num Lock or a gaming mode switch is not changing what the key does.
  5. Clean under the key with compressed air, holding the keyboard at an angle.
  6. On Windows, open Device Manager, uninstall the keyboard under Keyboards and restart to reinstall the driver.
  7. Try the keyboard on another computer. If the key fails there too, the switch or keyboard is faulty.

Key types twice

  1. Confirm it on the Chatter tab: press the key slowly and see whether double presses are counted.
  2. Clean the switch with compressed air, pressing the key a few times while you blow.
  3. Check the repeat settings: Windows Settings › Accessibility › Keyboard (Filter Keys) or Control Panel › Keyboard; on a Mac, System Settings › Keyboard › Key repeat rate and Delay until repeat.
  4. If your keyboard software has a debounce setting, raise it a little.
  5. On hot-swap keyboards, swap the switch with one from a key you rarely use. If the fault moves, replace the switch.
  • No paywall
  • No signup
  • Nothing uploaded

How to use the Keyboard Tester

  1. Press Start testing.
  2. Press every key on your keyboard; each one lights up and stays marked once it works.
  3. Check the Rollover tab by holding several keys at once, and the Chatter tab by typing normally.
  4. Open the Event log tab to see each key going down and up, with the time between events.
  5. Press Esc when you're done. Keys that never lit up need a closer look; the checklist under the tabs covers dead keys and double typing.

What this keyboard tester checks

  • Every key: an on-screen keyboard that lights each key as you press it and keeps it marked once it works
  • Rollover and ghosting: how many keys register at once, and which combinations drop out
  • Chatter: keys that double-type from a single press
  • Key details: the key name, physical code and whether it’s the left, right or numpad version
  • Event log: the last 20 key downs, repeats and ups with the time between them

If a key doesn’t work or types twice

  • Dead key: test it in another app first. Then try another USB port (not a hub), recharge or re-pair a wireless keyboard, check Fn Lock and Num Lock, and clean under the key with compressed air. On Windows, reinstalling the keyboard in Device Manager can fix a driver problem. If it fails on another computer too, the key or keyboard is faulty.
  • Double typing: confirm it on the Chatter tab, clean the switch, check the key repeat and Filter Keys settings, and raise the debounce time in your keyboard software if it has one. On hot-swap boards, swapping the switch shows whether the switch is the cause.

When to use it

  • Before buying a second-hand laptop or keyboard
  • When a key stops working or types twice
  • After spilling a drink or cleaning a keyboard
  • To check a new gaming keyboard’s rollover

Frequently asked questions

Why doesn't a key light up?

The key, its switch or the keyboard connection may be faulty. It may also be a key the browser never receives, like Fn, some media keys or Windows key shortcuts. Try the key in another app to compare.

What is keyboard ghosting?

Ghosting is when a keyboard can't register certain keys pressed together, so one of them never shows up. Hold the combination on the Rollover tab: if a held key doesn't light up, your keyboard can't handle that combo.

What is key chatter?

Chatter is when one press types the letter twice. It's usually a worn or dirty mechanical switch. The Chatter tab flags any key that registers two presses less than 50 ms apart.

How do I fix a key that types twice?

Confirm it on the Chatter tab by pressing the key slowly. Then blow compressed air into the switch while pressing it, check that your key repeat or Filter Keys settings are normal, and raise the debounce time if your keyboard software has one. If it keeps happening, the switch needs replacing.

What does the event log show?

The last 20 key events, newest first: each key going down, repeating or coming back up, with the time since the previous event. A key that goes down without coming up, or two downs only a few milliseconds apart, points to a stuck or chattering key.

Does this keyboard test record what I type?

No. Everything runs in your browser. Keys light up the on-screen keyboard and fill the event log on this page only; they are never saved or sent anywhere, and Reset clears them.

Why does the keyboard layout look different from mine?

Choose Full, TKL or Laptop, US or UK, and turn on Mac keys to match your keyboard. Keys are matched by position, so tests work on any layout.

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