How to use the Keyboard Tester
- Click the keyboard area once so the page has focus (switch any IME to English).
- Press each key: it lights up while held and keeps a tested colour, and the counters increase.
- Hold several keys at once (for example Q W E R + Space) to see the maximum simultaneous keys and judge NKRO or 6KRO.
- Watch for possible chatter warnings, test any keys in the untested list, then copy the summary.
Dead keys and key chatter
A dead key produces no event at all. Chatter is when one press registers twice, usually from oxidised or dusty mechanical switches or tired contacts. The tool measures the gap between a key release and the next press of the same key and flags repeats under 30 ms as possible chatter. Try cleaning, reseating the keycap or raising the debounce time in the keyboard software.
NKRO, ghosting and 6KRO
N-key rollover means any number of keys can be held and recognised. 6KRO is the usual USB boot-protocol limit (six normal keys plus modifiers). Membrane keyboards may show ghost keys (an extra key you did not press) or blocking (a pressed key not detected) on some combinations. Hold more keys and watch the counter. Browsers and the OS may also restrict some combinations.
Keys a web page cannot see
Fn is usually handled inside the keyboard firmware and never reaches the browser. Windows/Command, Print Screen, some media keys and system shortcuts such as Alt+Tab or Ctrl+W are taken by the OS or browser first. If these keys do not light up, they are not necessarily broken; confirm with your system’s own tools.
Frequently asked questions
Is what I type recorded?
Key names and counts are shown in page memory only, never stored or uploaded, and cleared when you close the page. Do not type passwords or other sensitive text in the test area.
Why does a key not respond?
It may be faulty, or it may be captured by the OS or browser (Fn, Windows, Print Screen, media keys), or an IME may be active. Switch to an English input method and see the section on keys a web page cannot see.
What is the difference between ANSI and ISO?
ANSI (US) has a single-row Enter and a long left Shift. ISO (European) has an inverted-L Enter and an extra key next to the left Shift. Pick your layout so the untested-key count is accurate.
Can I test a Mac keyboard?
Yes. Turn on Mac labels to show Command and Option. Command shortcuts may trigger browser actions, so press those keys on their own.
How do I know if my keyboard has NKRO?
Hold down as many normal keys as you can and watch the maximum simultaneous keys. More than six usually indicates NKRO; stopping at two or three is typical of a membrane matrix limit.