A keyboard test is a page that shows which keys your computer actually receives when you press them. This one draws a full keyboard (Windows US, Windows Korean or Mac layout) and lights each key as the browser gets its signal, then counts how many keys were held at once and flags possible key chatter. It reads the standard KeyboardEvent code of each key, so the result does not depend on your input language.
| What you see | What it means |
|---|---|
| Key is solid green while held (Held now) | The browser is receiving the key-down signal right now |
| Key turns pale green after release (Pressed) | The key worked at least once; it counts toward Keys tested |
| Key stays plain (Not pressed yet) | No signal received yet. Press it again; if it never lights, the key or switch is faulty |
| Most keys at once stops at 6 even with more fingers down | The keyboard is reporting 6-key rollover (6KRO) |
| Possible chatter: 1× (E 1×), shortest re-press gap 10 ms | One press of E arrived as two presses 10 ms apart: a sign of a worn or dirty switch |
| Fn key dimmed on the Mac layout | Normal. Fn is handled inside the keyboard and never reaches the browser |
How to use the keyboard test
Pick your layout, then press every key once and watch the counter. The Keys tested number goes up by one for each different key that lights, so you can see at a glance when a key is missing. On a Mac the Mac layout is selected for you.
The Last key line shows four values for the most recent press: key (the character it would type), code (the physical key, such as KeyA or ShiftRight), keyCode and location (1 = left, 2 = right, 3 = numpad). If a key lights the wrong spot on the drawing, check code: a remapping tool or the wrong layout in the operating system usually explains it. Use Reset to start over. Nothing you type is stored or sent; it is handled on this page only.
Key rollover test: NKRO vs 6KRO
Hold down as many keys as you can and read Most keys at once. That number is your keyboard's rollover as the browser sees it.
Many keyboards top out at six regular keys. The reason is the USB HID boot protocol: its keyboard report is 8 bytes, one byte for modifier keys, one reserved byte and six slots for key codes. Ctrl, Shift, Alt and the Windows or Command keys are bits in the modifier byte, so a 6KRO keyboard can still add those on top of six regular keys. N-key rollover (NKRO) keyboards use a different report and can send every key at once, though some of them fall back to 6KRO in certain modes or ports.
A realistic gaming check is W + A + S + D with Shift and Space. If all six stay solid green, rollover is not your problem.
Keyboard ghosting test
Ghosting is a key that lights up even though you never pressed it. It happens on cheaper keyboards whose key matrix cannot tell three held keys from four, so pressing three keys at the corners of a rectangle in the wiring makes a fourth appear.
Most keyboards block this instead: the third or fourth key simply does not register. On this test that looks like a key that stays plain while you hold a combination, then lights fine on its own. If that combination matters to you (a game binding, for example), try a different set of keys.
Key chatter test (double typing)
Chatter is one physical press that the computer receives as two or more. The test flags any press that starts less than the chatter threshold after the same key was released. The default is 50 ms, with 30 ms and 80 ms options. A person deliberately tapping the same key again usually needs longer than that, so a hit under 50 ms almost always means the switch bounced.
Use 30 ms if you type very fast and see false flags. Use 80 ms to catch a switch that is starting to fail. Auto-repeat from holding a key down is ignored. If one key keeps showing up, clean under it with compressed air and test again; if it persists, the switch needs repair or replacement.
Mac keyboard test and keys browsers cannot see
A few keys never show up, and that is not a fault. The Fn key is handled inside the keyboard, so it is dimmed and not counted. On macOS, keys released while Command is held often send no key-up event, so the test releases every held key when Command comes up. Media keys and some macro keys are also not passed to browsers.
On Windows, the operating system takes the Windows key and Print Screen first, so they may light late or not at all. Browser shortcuts such as Ctrl + W still work during the test, so avoid them.
The Windows (Korean) layout adds the Han/Yeong and Hanja keys found on Korean keyboards. They often send no key-up, so the test releases them after a short delay.
FAQ
Why is my keyboard test stuck at 6 keys?
Your keyboard is in 6-key rollover mode, the limit of the USB boot protocol report. Modifier keys such as Shift and Ctrl can be added on top. Some keyboards switch to NKRO with a key combination or software setting; check the maker's manual.
Does this keyboard test work on a laptop?
Yes. Built-in laptop keyboards send the same key signals. Laptop keyboards often have lower rollover and may block some three-key combinations, so a low Most keys at once number is normal there.
Why does the Fn key not light up?
Fn changes what other keys send inside the keyboard itself. The browser never receives an Fn event, so no website can test it.
Is anything I type recorded?
No. Key presses are handled only on this page. Nothing is saved or sent anywhere.
Sources: W3C UI Events KeyboardEvent code Values · MDN Web Docs: KeyboardEvent · USB-IF Device Class Definition for HID 1.11, Appendix B (boot keyboard report) · Updated 2026-10-14