How to test your keyboard
Press every key on your keyboard, one at a time. While testing, the page catches every key, so press Esc when you want to scroll or use links again, and click the keyboard to resume. A key turns yellow while you hold it and green once it has worked. Any key that stays white after you press it is not sending a signal. The counter shows how many keys of the selected keyboard size you have tested.
Pick the size that matches yours: Full-size with a number pad, TKL (tenkeyless, no number pad), a compact 60% board, or a Mac keyboard with Command and Option keys. The layout (QWERTY, AZERTY, QWERTZ, Dvorak or Colemak) is detected from the keys you press, and you can also choose it yourself.
Test for ghosting and key rollover
Hold down several keys at the same time, for example A S D F J K, and check that every one of them is yellow. "Most keys at once" records the highest number of keys your keyboard reported together. If fast typing drops letters, low rollover is often the reason.
Check key repeat
Hold down a single key. "Key repeat" shows the delay before the key starts repeating and how many times per second it repeats. These values come from your operating system's keyboard settings.
Keyboard works? Put it to use
Check your speed with the typing test, or learn which finger belongs on each key in the free typing lessons.
Frequently asked questions
Why doesn't the Fn key light up?
The Fn key is handled inside the keyboard itself and never sends a signal to your computer, so no website or app can detect it. Media keys (volume, brightness) often work the same way.
Why does Print Screen only light up when I let go?
On Windows the Print Screen key only reports when it is released. The tester still marks it as working.
A key stays yellow on my Mac. Is it stuck?
Probably not. While Command is held down, macOS doesn't report when other keys are released. Let go of Command and the tester clears every key.
What is keyboard ghosting?
Ghosting happens when you press several keys together and some of them don't register. Hold down more and more keys and watch "Most keys at once". Many office keyboards stop at 2–6 keys, while gaming keyboards with n-key rollover register them all.
What is the difference between event.key and event.code?
event.key is the character your keyboard layout produces, and event.code is the physical key position. On a French AZERTY keyboard the key next to Tab gives key "a" but code "KeyQ", because it sits where Q is on a US keyboard.
Can I test my keyboard on a phone or tablet?
Yes, if you connect a physical keyboard over Bluetooth or USB. The on-screen keyboard of a phone doesn't report which key you pressed, so it can't be tested this way.