Full-size (104/105 keys)
Main block, navigation cluster and number pad.
Keyboard Test: Check Every Key
Click the keyboard and press every key once. Each one lights up while held and turns green once it has worked. A key that fires twice from one press is flagged as chatter — the reason a keyboard types double letters.
Updated · 2 sources
Click the keyboard below, then press every key once. Keys light up while held and stay green once they have worked. Click a key on the picture to mark it as not on your keyboard.
1 · Layout
2 · Press every key
Click here to start testing
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Key log
Short answer
Click the keyboard picture, then press every key once. Working keys turn green, and Show my result lists any key that never registered. A key that fires twice from one press is flagged as chatter — the cause of double typing. The test uses physical key positions, so AZERTY, QWERTZ and other layouts light up the right key.
How to use it
- Pick the layout. Full-size, tenkeyless or laptop; tick ISO for UK and European keyboards and Mac for Command and Option keys. Pressing the extra ISO key switches automatically.
- Click the keyboard picture. Keys are only captured while the picture is active, so the rest of the page still works normally. Click outside to pause.
- Press every key once. Keys follow physical position, so any language layout works. Click a key on the picture to skip one your keyboard does not have.
- Show the result. Keys that never registered are listed, with system keys such as the Windows key and Print Screen separated out.
How this keyboard test works
It checks every key, with nothing to install, and flags double typing automatically. The test listens to the physical key code of each press, not the character, so the picture lights up the right key whatever your language layout. It shows three values for the last key: Key (the character your layout produced), Code (the physical position, such as KeyA or IntlBackslash), and the older keyCode number some games and scripts still use.
Choose the layout that matches your keyboard so the count is fair: full-size with a number pad, tenkeyless without one, or laptop / 75% with arrows only. Click any key on the picture that your keyboard does not have and it is skipped.
Keyboard double typing: how chatter is detected
A key that types two letters from one press is chattering: the metal contacts inside the switch bounce and the keyboard reports two presses. This keyboard chattering test flags a key automatically when it fires again within 50 ms of the previous press, or within 25 ms of being released — faster than a finger can re-press a key. Many key testers leave you to spot doubles in a log; this one marks the key red and counts each double-fire.
To fix it:
- Clean it. Pull the keycap if you can and blow out the switch, then press it firmly 20–30 times.
- Raise the debounce time in the keyboard software, if it has the option.
- Replace the switch on a hot-swap mechanical keyboard — it takes seconds.
- On a laptop, a chattering key usually means debris under the keycap or a worn keyboard that needs replacing.
A key does not light up
| What you see | Likely cause |
|---|---|
| One key dead, on two computers | Switch or membrane failed |
| A group of nearby keys dead | Spill or a broken matrix trace |
| Number pad dead | Num Lock is off |
| Windows key, Print Screen, F11, F12 | Taken by the system or browser first |
| Fn, brightness, media keys | Handled inside the keyboard or by the system |
Testing a keyboard in two minutes
- Every key once. Go row by row, including the F1–F12 row, arrows and the number pad. Any key that has not turned green at the end is your list of dead keys.
- The keys you use most, ten times each. Space, E, A, Backspace and Enter wear first. This keyboard key test flags any key that types twice.
- Hold-and-roll. Hold Shift and type a word, then hold a game key (W) and tap others. For a full rollover check, use the Keyboard Ghosting Test.
Do the same on a second computer before deciding a key is broken. If a key fails on both, it is the keyboard; if it only fails on one, it is a setting, a driver or a remapping tool.
Keyboard checker for Mac keyboards
Tick Mac keys to label Command and Option. On a Mac, browsers do not report releasing other keys while Command is held, so this test clears all held keys when you let go of Command — keys will never look stuck.
ISO and ANSI layouts
UK and European (ISO) keyboards have an extra key between left Shift and Z, and a tall Enter key. Press that extra key and the picture switches to ISO automatically.
Layouts
Tenkeyless
No number pad. Most gaming and many office keyboards.
Laptop / 75%
No navigation cluster; arrows only. Skip any keys your model lacks.
ISO
UK and European: an extra key next to left Shift and a tall Enter.
If something goes wrong
A key types twice
That is chatter: the switch bounces past the debounce filter. Clean it and press it firmly a few dozen times; on mechanical keyboards raise the debounce setting.
Number pad does nothing
Num Lock is probably off. Press it and try again.
Windows key or Print Screen stays grey
The system takes those before the browser sees them. Check them in normal use.
Several keys in one area fail together
That points at the keyboard matrix or a spill, not single switches. Test on another computer.
FAQ
How do I test my keyboard online?
Click the keyboard picture on this page and press every key once. Working keys turn green, the count shows how many are left, and Show my result lists any key that never registered.
Why is my keyboard double typing?
The switch under that key is chattering: its contacts bounce and the keyboard sends two presses. This keyboard checker flags any key that fires again faster than a finger can re-press it. Cleaning, a higher debounce setting, or replacing the switch fixes it.
Does this keyboard tester work with any language layout?
Yes. It uses the physical key position (KeyboardEvent.code), so AZERTY, QWERTZ and other layouts light up the right key on the picture. The Key box shows the character your layout produces.
Why doesn’t the Fn key light up?
On most laptops and compact keyboards Fn is handled inside the keyboard and never sent to the computer. Brightness and media keys may also be handled by the system first.
Is anything I type sent anywhere?
No. The key tester runs in your browser and keeps nothing after you leave the page.
Sources
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