Keyboard Tester

Highlights every key you press on a 104-key layout and finds dead ones

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About this tool

This tool shows you which keys on your keyboard are not registering. It draws a 104-key layout, paints the key you are holding in blue and leaves every key you have pressed in green, so once you have worked across the board only the dead keys remain uncoloured. Detection uses the physical position (event.code) rather than the character produced (event.key), so it works with any keyboard layout or input method switched on.

How to use

  1. Press any key. Its position lights up the moment you press it.
  2. Work across the board from the top left and watch for keys that never turn green.
  3. Hold several keys at once to see the maximum simultaneous count (N-key rollover).
  4. Read the code, key and keyCode values in the log below, and press Reset to start over.

Frequently asked questions

Does it work with a non-English keyboard layout?
Yes. The tool reads event.code, which is the physical position of the key. Whether that key produces a, ั„ or ใ…, the code is still KeyA, so you do not have to switch your input method off.
I pressed F5 and the page did not reload.
That is deliberate. Reloading mid-test would wipe everything you have checked so far. Switch to Browser shortcuts allowed and normal behaviour comes back.
Why are Ctrl+Alt+Del and the Windows key not blocked?
The operating system intercepts those before the browser ever sees them, and the same goes for Alt+Tab and Alt+F4. Tab is left working on purpose so you can leave the page without a mouse.
Some keys are ignored when I hold several at once.
That is common on membrane keyboards: keys sharing a circuit block each other, so later presses are dropped. Gaming keyboards advertise N-key rollover precisely to avoid this.

This tool only checks the signals your keyboard sends to the browser. It cannot tell you whether a missing signal comes from the switch, the cable or the driver. Everything you type stays in your browser and is never sent to a server.

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