Toetsenbordtester.

How do I find a dead key on my keyboard?

Start the test and press every key in turn. Keys turn green once they have registered at least once, so any key still unlit after you have pressed it is either dead, has a failing switch, or is being intercepted by system software before it reaches the browser.

What is the difference between event.code and event.key?

event.code identifies the physical key position and does not change with your layout or with modifiers - the key left of Backspace is always "Equal". event.key is the character actually produced, so the same physical key gives "=" or "+" depending on Shift, and different values on a non-US layout. If code is correct but key is wrong, your hardware is fine and your OS layout is the problem.

Does this test hijack my browser shortcuts?

No. Only keys that would scroll the page - space and the arrow keys - are swallowed while the test is running, and only when no modifier is held. Ctrl/Cmd combos, the function keys including F5 and F12, Tab and Escape are all passed through to the browser, so you are never trapped in the test.

Why do some keys never appear?

Media keys, Fn, and some laptop hotkeys are handled entirely by the keyboard firmware or the operating system and never generate a browser keyboard event. Their absence here does not mean they are broken. The same applies to keys captured by a global shortcut in another application.

Is this the same as a typing speed test?

No. This tool checks that your hardware registers every key correctly. If you want words per minute and accuracy instead, use the typing speed test at /productivity/typing-test.