About this tool
This free keyboard test lights up each key on an on-screen keyboard as you press it. Keys you have tested stay green, so you can work across the whole board and see at a glance which ones never responded. It also shows the key name, event.code and keyCode for the last key pressed.
Everything runs in your browser — nothing you type is stored, sent or logged anywhere.
Features
- Full keyboard — function row, main block, navigation cluster and numpad
- Tested keys stay green so you can spot the ones that never lit up
- Live count of keys held down — the quickest way to test ghosting
- Key details: event.key, event.code and the legacy keyCode
- ANSI and ISO layouts (the Enter and left-Shift difference)
- Reset at any time and start a fresh sweep
Finding dead keys, stuck keys and ghosting
Three different faults look similar from the outside, and this tool separates them.
A dead key never lights up. Work along each row in order and see what stays grey at the end. If a whole row or a diagonal group is dead, suspect the ribbon cable or the controller rather than the individual switches — physically separate keys share wiring inside the matrix.
A stuck key is the opposite: it lights up and stays lit after you let go, and the "held down now" count never returns to zero. That is usually debris under the cap, but it is also what a failing switch looks like just before it goes.
Ghosting is about how many keys work *at once*. Press three or four keys together and watch the counter. On a cheap membrane keyboard it stops rising — press W, A and Shift and only two register — because the matrix cannot tell certain combinations apart. Gaming keyboards advertise "n-key rollover" precisely to avoid this. It is a design limit, not a fault, but it explains why a character in a game sometimes refuses to move and shoot at the same time.
One honest caveat: the operating system takes some combinations first. Windows keeps the Windows key, Alt+Tab and Ctrl+Alt+Delete; browsers keep a few shortcuts of their own. A key that never reaches this page is not necessarily broken — it may simply have been intercepted before the page could see it.
Common uses
- Check a second-hand or repaired keyboard before relying on it
- Find which key is stuck when text repeats by itself
- Test rollover before buying a keyboard for games
- Look up the event.code or keyCode of a key while writing software
- Confirm a laptop keyboard after a liquid spill or a cleaning
How to use it
- Press any key — it lights up green on the on-screen keyboard
- Work through the whole board — tested keys stay green, so the untested ones stand out
- Hold several keys together and watch the "held down now" count to check ghosting
- Switch to ISO if your Enter key is tall and L-shaped rather than wide and flat
- Press Reset to clear the green and start again
Good to know
- Nothing is logged. Key presses are handled on the page and never leave your device
- Keys are matched by physical position (event.code), so the test works on any language layout — the printed faces just show the US legend
- A few keys cannot be captured: the Windows/Command key, Alt+Tab, Ctrl+Alt+Delete and some browser shortcuts belong to the system
- Fn is invisible. On most laptops it is handled inside the keyboard itself and never reaches the browser, so it will not light up — that is normal
- F5 and F12 are deliberately left to the browser so a test cannot reload the page or open developer tools
- If a key lights up but types the wrong character, the hardware is fine — that is a layout setting in your operating system
- Media and macro keys often report no event.code; the tool will say so rather than pretend they failed
Related tools
- Typing Speed Test — now that the keys work, see how fast you are
- Microphone Test — check the audio hardware
- Webcam Test — check the camera
- Online Notepad — somewhere to type once everything works
