How to test your keyboard
Work along the board one row at a time and press each key firmly once. A key turns orangewhile it is held down and stays highlighted once released, so the untested keys are whatever is still grey. The counter tells you how many of the layout's keys have registered, and the panel below lists exactly which ones haven't.
If you're on a laptop, switch to Laptop layoutso the number pad isn't counted against you. Media keys, Fn and programmable macro keys aren't part of the standard layout — press them and they appear under “Extra keys detected”.
What this test can find
The test reads the browser's raw key events, so it sees what the keyboard actually reports rather than what Windows or macOS decides to do with it. That makes four common faults visible.
- Dead keys — press it and nothing lights up. Usually debris under the cap, a failed switch, or a damaged trace on a membrane board.
- Stuck keys— a cap stays orange after you let go. That single key is holding the whole keyboard hostage and explains “typing on its own” behaviour.
- Ghosting and rollover limits — hold six or seven keys at once and watch the max figure. Cheap membrane keyboards stop registering at three to six simultaneous keys, which is what makes them frustrating for gaming.
- Wrong character mapping— the key registers but produces the wrong letter. Compare the cap you pressed with the “Character” readout; a mismatch means your OS keyboard layout is set to the wrong language, not a hardware fault.
Why some keys still won't register
A grey key is not always a broken key. Four limits are worth knowing before you conclude your keyboard is faulty.
| Key | Why it may not show |
|---|---|
| F11, F12, F5 | The browser claims these first (fullscreen, developer tools, reload). A web page cannot override them. |
| Windows / Cmd key | Handled by the operating system before the browser sees it, so the Start menu or Spotlight may open. It usually still registers. |
| Fn | Fn is wired inside the keyboard itself and produces no browser event on most laptops. Test what Fn does instead — Fn + brightness, for example. |
| PrtSc, Pause, Insert, NumLock | Absent on most Mac keyboards and many compact boards, so they stay grey and can be ignored. |
Ctrl and Cmd combinations are deliberately let through so you can still reload or switch tabs while the test runs. Use Pause capture if you need the page to behave normally again.
A key is dead — now what?
Try the cheap fixes first, in this order. Shut the machine down and clean around the key with compressed air; a single dead key on an otherwise healthy board is debris far more often than failure. Then check the OS layout (Windows: Settings → Time & language → Language & region) in case the problem is mapping rather than hardware. On a desktop, try the keyboard on a different USB port and a different computer — that isolates the keyboard from the port.
If a key is genuinely dead on an external keyboard, replacement is almost always cheaper than repair. On a laptop, a single failed key means a keyboard assembly swap, so an external keyboard is the sensible stopgap — see our guide to the best mechanical keyboards for typing, where hot-swappable switches let you replace one failed switch instead of the whole board.
Checking a second-hand laptop? Keep going: the mouse and trackpad test covers the other input device, and the dead pixel test checks the screen.
Frequently asked questions
Is this keyboard tester safe? Are my keystrokes recorded?
It is safe. The test runs entirely as JavaScript inside your own browser tab and there is no server involved — no keystroke, and nothing you type, is transmitted, logged or stored by TopTechs. Closing the tab discards everything.
Does it work on a phone or tablet?
Only with a physical keyboard attached. An on-screen keyboard doesn't produce the hardware key events this test reads, so pair a Bluetooth keyboard to your phone or tablet and it will register normally.
How do I test whether my keyboard has ghosting?
Hold down as many keys as you can at once — six or more, spread across the board — and read the maxfigure next to “Held now”. If it stops climbing at three or four, your keyboard cannot register those combinations simultaneously. Full N-key rollover keyboards keep counting.
Why does my Caps Lock look stuck?
Caps Lock, Num Lock and Scroll Lock are toggles, and some systems — macOS in particular — only report half of the press. This tester releases those three keys automatically after half a second so they never appear falsely stuck.