How to use
- 1Choose the layout that matches your keyboard (US QWERTY, German QWERTZ, Turkish Q, Spanish, Arabic or Russian).
- 2Press keys one by one — held keys turn green and tested keys stay marked.
- 3Read the key, code, keyCode and location of the last key, plus the recent key history.
- 4Hold several keys at once to test rollover and ghosting, then press Reset to start over.
How to find a broken key
Work across the keyboard row by row. Every key that registers stays marked, so a key that never lights up is either dead or not reaching the browser. If one key press shows up as several repeats, the switch may be chattering — the “Repeats” counter shows how many auto-repeat events arrive while you hold a key, which is normal only when you hold it down on purpose. The panel shows the event’s key (the character), code (the physical key position) and keyCode, which is handy for debugging games and shortcuts.
Ghosting and key rollover
Hold several keys at the same time, for example A S D F J K L. “Max simultaneous” is the number of keys your keyboard reported together. Cheap membrane keyboards are often limited to 2–6 keys in some combinations (2KRO/6KRO), while many gaming and mechanical keyboards support n-key rollover. If a key you are holding doesn’t light up, that combination is blocked (ghosting/jamming) — important for games where you press movement keys and actions together.
Keys the browser cannot see
The Fn key and many media or brightness keys are handled by the keyboard firmware or the operating system and never reach a web page. System shortcuts such as Alt+Tab, the Windows key or Cmd+Tab, and browser shortcuts like Ctrl+W, may be captured before the page sees them. Test those keys on their own rather than in combinations.
Frequently asked questions
Why doesn’t the Fn key light up?
Fn is handled inside the keyboard itself and is never sent to the computer as a key press, so no website can detect it.
What is the difference between key and code?
“key” is the character produced with your current layout (for example “z” or “y”), while “code” identifies the physical key position (KeyZ), regardless of layout.
How many keys can my keyboard press at once?
Hold down as many keys as you can; the “Max simultaneous” counter shows how many were registered together. Try different combinations, as limits often depend on which keys share a matrix line.
Does it work with laptop and wireless keyboards?
Yes. Any keyboard that types in your browser can be tested, including laptop, Bluetooth and USB keyboards.
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