Keyboard Tester

Click the test area and press keys: each one lights up on the on-screen keyboard while it is held and stays marked, with a press count, once it has registered. The counter shows how many of the layout's keys you have tested, and a "Not yet tested" list names the ones left — the fastest way to find a dead key.

Pick the layout that matches your board — full-size, tenkeyless, 75% or 60%, in ANSI (US) or ISO (UK/EU) form. Pressing the extra ISO key beside left Shift switches to ISO automatically, and in Chrome and Edge the legends follow your OS keyboard layout, so AZERTY and QWERTZ boards show their own letters.

While the test area has focus it keeps Tab, Space, Backspace, the arrows and the F-keys to itself, so you can test them without the page scrolling or jumping away. Press Esc twice quickly to leave it.

Rollover and ghosting test

"Held now" and "Max simultaneous" count the keys the browser sees at the same time. Hold keys down one after another: a keyboard in USB boot mode (6KRO) tops out at six regular keys plus modifiers, while an NKRO board keeps counting. Budget membrane keyboards often share wiring between keys, so some three-key combinations either block the third key or make a key you never pressed light up — that is ghosting. Try the combinations your games use, such as W+A+Shift+Space.

Chatter test

A worn or dirty mechanical switch can bounce, sending a second keypress a few milliseconds after you let go — the classic "keyboard types double letters" fault. The tester flags any keydown that arrives within the chatter threshold (40 ms by default, adjustable under Options) of the same key's release, and lists each chattering key with its count and shortest gap. Human double-taps are almost always slower than 60 ms, so real chatter stands out.

Common uses

• Check a new, used or repaired keyboard for dead keys before the return window closes
• Find out whether a gaming keyboard really has N-key rollover, or where a membrane board ghosts
• Confirm which switch is double-typing before you clean or replace it
• Look up the KeyboardEvent.code, key and location a key sends, for writing shortcuts or remapping

Example

Tap E once on a switch that double-types

↓ down  e  KeyE  standard  chatter (6 ms)
↑ up    e  KeyE  standard  held 48 ms
↓ down  e  KeyE  standard

The newest event is on top: the key was released after 48 ms, then a second keydown arrived only 6 ms later — far faster than a finger — so E is listed under Chatter.

Limitations

• Browsers never see some keys: Fn is handled inside the keyboard, and the operating system keeps shortcuts like Alt+Tab, Ctrl+Alt+Del, ⌘+Tab and many Windows-key combinations, plus media and brightness keys on most laptops.
• On macOS, keys pressed while ⌘ is held do not report their release; the tester releases them when ⌘ comes up.
• Rollover is measured as the browser receives it. Some keyboards switch between 6KRO and NKRO with a key combination or a driver setting.
• Timing comes from browser event timestamps, which are precise to about a millisecond — plenty for chatter, but not a lab-grade latency measurement.

How do I test my keyboard online?

Click the test area and press every key on your keyboard. Each key lights up while held and stays marked once it registers, and the counter shows how many of the layout's keys you have tested. Open the “Not yet tested” list to see exactly which keys have not responded.

How do I test keyboard ghosting?

Hold down combinations of three or more keys — for example Q+W+E, A+S+D or W+A+Shift+Space — and watch the on-screen keyboard. If a key you are holding does not light up, the board is blocking it; if a key you did not press lights up, that is ghosting. Membrane keyboards are the usual culprits.

What is N-key rollover and how do I check it?

N-key rollover (NKRO) means every key registers no matter how many are held. Many keyboards in USB boot mode are limited to 6-key rollover (6KRO): six regular keys plus modifiers. Hold keys down one at a time and read “Max simultaneous” — if it stops at six (plus Shift, Ctrl or Alt) your keyboard is running in 6KRO.

Why is my keyboard typing double letters?

Usually switch chatter: a worn or dirty mechanical switch bounces and sends a second press a few milliseconds after the first. Tap the suspect key 20 to 30 times at a normal pace; the tester flags any press that follows the key's release faster than the chatter threshold (40 ms by default) and shows the shortest gap it saw.

Why don't the Fn, Windows or media keys show up?

Fn is handled inside the keyboard and never sends anything to the computer. The operating system also keeps some keys and combinations for itself — Alt+Tab, Ctrl+Alt+Del, ⌘+Tab, many Windows-key shortcuts and often media or brightness keys — so no website can detect them. That does not mean the key is broken.

Does the keyboard tester work with ISO, AZERTY or QWERTZ keyboards?

Yes. Choose ISO for UK and European boards with the tall Enter key and the extra key beside left Shift — pressing that key switches the layout automatically. Keys are matched by their physical position, and in Chrome and Edge the legends follow your OS layout, so AZERTY and QWERTZ letters appear on the right keys.

Can I test a laptop keyboard with this tool?

Yes. Pick the 75% or 60% layout for the closest match, press every key, and use the not-yet-tested list to find dead keys. Laptops often ghost on three-key combinations and route media keys through Fn, so those may not appear here even when they work.

Is anything I type recorded or sent anywhere?

No. Key events are handled entirely in your browser and kept only in memory while the page is open — nothing is stored, logged to a server, or transmitted. Reset clears everything instantly.