Keyboard Tester Online

How to use

1. Click on the page once so it receives keyboard input, then press any key. It turns green on the virtual keyboard; the Last key and code boxes show what the browser received.
2. Go through the whole board row by row. Anything that stays grey after a firm press is a dead key (or one the browser cannot see — see the notes on Fn and media keys).
3. Hold down several keys at once — start with W+A+S+D+Space+Shift, then add more. Max simultaneous shows the highest number registered together.
4. Switch on Typing mode to type into a real text field and catch keys that register twice (chatter) or drop letters.
5. Reset clears the highlights so you can re-run a section after cleaning or re-seating a keycap.

What the tester checks and how

The page listens for keydown and keyup events and maps each one onto the drawn keyboard by its event.code — the physical key identity (KeyW, ShiftLeft, Numpad5), which does not change with your language layout. That lets the tester work the same for QWERTY, ЙЦУКЕН, AZERTY or any other layout: you see which physical switch fired, and the Last key box shows the character the OS produced for it.

Three faults show up immediately. A dead key never lights up. A stuck key lights up without being pressed, or stays "down" after you release it. Chatter — a worn switch that registers two presses for one — is visible in Typing mode as doubled letters. The Max simultaneous counter tracks how many keys the keyboard reported as held at the same moment, which is the rollover test described below.

A few keys are invisible to any browser: the Fn key is handled inside the keyboard and never reaches the OS, some media and power keys are intercepted by the system, and a handful of shortcuts (for example Ctrl+W closing the tab, or the Windows/Cmd key opening a menu) are taken by the OS or browser before the page sees them. Those keys aren't necessarily broken — test them in the OS.

Rollover, NKRO and ghosting explained

Rollover is how many keys a keyboard can register at once. N-key rollover (NKRO) means every key is detected independently no matter how many others are held. Cheaper keyboards use a switch matrix without diodes, and pressing three keys that form three corners of a rectangle in that matrix makes the keyboard see a phantom fourth press — that is ghosting. Modern keyboards avoid the phantom key by blocking (also called jamming) instead: the third key is simply ignored. By Wikipedia's Rollover article, diode-equipped keyboards eliminate both problems, and the USB "boot protocol" limits reports to six simultaneous keys plus modifiers, while the normal HID report protocol has no such limit.

Because the browser counts what the OS delivers, a keyboard in boot-protocol mode (some BIOS-compatibility modes and some Bluetooth stacks) will show 6 here even if it is capable of more. Check the keyboard's software for an NKRO toggle.

Testing after spilling a drink

Liquid is the most common reason people search for a keyboard tester. Order of operations matters:

1. Power off first. Unplug a USB keyboard; on a laptop, shut down immediately and unplug the charger. Don't test while it is wet — sugar and minerals in tea, cola or juice conduct and corrode.
2. Drain and dry. Turn the keyboard upside down, blot, then leave it keys-down for at least 24–48 hours. Rice does nothing useful; air flow does.
3. Then test here. Press every key, note the ones that stay grey (dead) and the ones that light up by themselves (stuck from residue). Use Typing mode to catch chatter.
4. Sticky but working keys usually recover after pulling the keycap and cleaning the switch stem with isopropyl alcohol. Dead keys on a mechanical board mean a switch to replace (hot-swap sockets make this a two-minute job); on a laptop it is usually the whole keyboard module.
5. Re-test in a week. Corrosion is slow; keys that pass today can fail later, so keep the tester bookmarked.

Key codes, layouts and gaming use

The code box shows event.code, the physical identifier that games and remapping tools use — handy when you are binding keys in a config file and need to know whether a key is Backquote or IntlBackslash, or which of the two Alt keys you just hit. The Last key box shows event.key, the character after your layout is applied — that is what a chat box receives.

For gamers the quick check is the movement cluster: hold W, A, D, Shift, Space, Ctrl and one or two ability keys together and see whether the counter matches the number of fingers down. If it doesn't, the keyboard is blocking a combo, and that is the key that "sometimes doesn't work" in a fight. Laptop keyboards are the usual offenders; a 6KRO or NKRO external keyboard fixes it.

What makes our keyboard tester different

• Layout-independent: keys are matched by physical code, so Cyrillic, German or Japanese layouts light up the right keys.
• Rollover counter built in — the maximum number of keys held together is tracked live.
• Typing mode to catch chatter and dropped letters in a real text field.
• No ads over the keyboard, no downloads, no plugins, works with USB, Bluetooth and built-in keyboards.
• Everything in the browser, no account.

Privacy: keystrokes are processed by the script on this page only. Nothing you type is transmitted or stored — the page has no server component, and Typing mode text stays in the text box until you reset it.

FAQ