Hold multiple keys simultaneously. The app measures how many physical keys the browser actually registers through KeyboardEvent.code.
Keys at maximum:
1 press2345+Colors remain until you press Reset
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About the Online Keyboard Test
Check every key of your keyboard in the browser: see keystrokes light up in real time, measure key rollover, detect ghosting and find stuck or chattering keys. Works with laptop keyboards, mechanical keyboards and external USB or Bluetooth keyboards alike.
What is key rollover and how do I test it?
Key rollover is the number of keys the keyboard can register at the same time. Press and hold multiple keys at once and count how many stay lit. 6-key rollover (6KRO) is typical for office keyboards; NKRO (unlimited) is common on gaming keyboards. Gaming matters: with low rollover, combinations like W+A+Shift+Space can drop a key.
What is keyboard ghosting?
Ghosting happens when the keyboard's matrix cannot distinguish certain key combinations, so it either drops a pressed key or registers a key you never pressed. Hold three keys that form a rectangle in the key matrix (for example A+S+D plus a nearby key) and watch for missing or phantom keystrokes.
How do I find a stuck or chattering key?
A stuck key shows as permanently pressed the moment the test starts. Chatter (one press registering multiple times) shows up in the counters: press each key once and check that its count increased by exactly one. Chattering switches are a common fault on worn mechanical keyboards.
Why do my Fn and some media keys not register?
On most keyboards, the Fn layer is handled inside the keyboard's own firmware and never reaches the operating system, so a browser cannot see it. That is a hardware design limitation, not a defect.
Does the test send my keystrokes anywhere?
No. The page makes no network calls whatsoever; keystrokes are processed locally and never leave your browser.