Keyboard Tester — Test Every Key
See every key light up as you press it, with codes, rollover, chatter and repeat rate.
Keyboard test
Press Start testing or click the keyboard, then press keys.
Full screen: hold Esc for two seconds to leave.
This test needs a physical keyboard. On-screen keyboards on phones and tablets do not report physical keys — connect a Bluetooth or USB keyboard.
Not yet pressed
Rollover and ghosting
Hold down several keys at once to measure rollover.
Chatter (double presses)
No chatter so far. Type normally for a while; keys that bounce show up here.
| Key | Presses | Possible chatter | Shortest gap |
|---|
Repeat delay and rate
Hold any key for about two seconds. The delay and rate are your system’s keyboard settings.
Event log
| Event | key | code | location | keyCode | Held | Note |
|---|
Events appear here, newest first (the last 200).
About the Keyboard Tester — Test Every Key
Press Start testing and type: every key lights up on the on-screen keyboard while it is down and stays marked once it has worked, so a dead key is easy to spot. Choose a full-size, tenkeyless (TKL) or laptop keyboard, the ANSI (US) or ISO (UK/European) shape, and Windows or Mac labels.
Beyond "does it work", the tester checks what keyboard reviews check: how many keys register at once (rollover) and whether some combinations drop keys (ghosting), presses that repeat by themselves straight after a release (chatter, the cause of double letters), and your system’s auto-repeat delay and rate. A log shows each event’s key, code, location and legacy keyCode — handy for developers. Nothing you type is sent anywhere or kept.
How to use it
- Pick the keyboard type, ANSI or ISO, and Windows or Mac. In Chrome and Edge the keys can show your own layout’s characters (for example AZERTY).
- Press Start testing (or click the keyboard). The page now records every key; press Esc three times quickly to stop.
- Press each key once. Keys turn green after they have worked; the counter shows how many are left, and Not yet pressed lists them.
- For rollover and ghosting, hold down as many keys as you can, or pick a combination under Rollover and ghosting and hold all its keys together.
- Watch Chatter for double presses, hold a key for two seconds to measure the repeat rate, and copy the Event log if you need the details.
Examples
Press every letter once
All letters green except one that never lights up
If a key never lights up — and the system keyboard viewer agrees — the key or its switch is faulty.
Hold W, A, S, D, Left Shift and Space
Held now: 6 · combination complete
If one of them never lights up while the others are held, the keyboard is ghosting or blocking that combination.
A worn switch types "ee" for one press
Possible chatter: E, second press 9 ms after the release
Nobody presses a key twice within a few milliseconds; that is the switch bouncing.
Press the key labelled A on a French AZERTY keyboard
key "a" · code "KeyQ" · location 0
code names the physical position (where Q is on a US keyboard); key is the character your layout gives it.
Common uses
- Checking a new, second-hand or repaired keyboard, or a laptop before buying it.
- Finding the cause of double letters or missing keys.
- Comparing gaming keyboards for rollover and anti-ghosting.
- Developers looking up the key and code values for keyboard shortcuts.
Rollover and ghosting
Rollover is how many keys a keyboard reports at the same time. Many USB keyboards report at most 6 ordinary keys plus the modifiers (Ctrl, Shift, Alt, Windows/⌘), because that is what the basic USB keyboard report holds; gaming keyboards often report every key ("n-key rollover"). Hold more and more keys: Most at once shows the highest number the page received.
Ghosting happens on cheaper keyboards whose keys share wiring: some combinations of three or more keys are blocked, or make a key that was not pressed appear. Pick a combination such as W A S D + Shift + Space and hold all of its keys; the list shows which ones the page received. A key that stays missing while the others are held is blocked in that combination. The browser and the operating system can only report what the keyboard sends.
Chatter (double typing)
Key switches bounce for a few milliseconds when they close, and the keyboard’s firmware filters that out. A worn, dirty or faulty switch can bounce for longer, so one press arrives as two. The tester flags any press of a key that comes less than the chatter threshold (40 ms by default) after that key was released — no one can deliberately press the same key again that quickly, so raising the threshold a little is still safe. If one key keeps chattering, cleaning it or replacing the switch usually helps.
Repeat delay and rate
Hold a key and, after a pause, the operating system starts repeating it. The tester measures the delay before the first repeat and the rate of repeats per second. Both are system settings, not properties of the keyboard: change them in Windows under Control Panel › Keyboard ("Repeat delay" and "Repeat rate"), in macOS System Settings › Keyboard ("Key repeat rate" and "Delay until repeat"), or in your Linux desktop’s keyboard settings.
Keys the operating system or browser keeps
Some keys never reach a web page, or only partly, whatever the keyboard does:
- Fn is handled inside the keyboard and normally sends no key of its own (the W3C code list says so too); it is shown with a dashed outline.
- Windows key shortcuts (Start menu, Win+L), Alt+Tab, Alt+F4 and Ctrl+Alt+Del are taken by Windows; Ctrl+Alt+Del can never be captured by any application.
- Print Screen on Windows is usually taken for screenshots; often only its release reaches the page, which still counts as working.
- On a Mac, ⌘+Tab, ⌘+Space and Mission Control shortcuts are taken by macOS and ⌘+Q by the browser, and while ⌘ is held the browser does not receive the release of other keys — the tester releases them when ⌘ comes up.
- Browsers keep shortcuts such as Ctrl/⌘+W, Ctrl/⌘+T, Ctrl/⌘+N and Ctrl+Tab; test those keys on their own.
In Chrome, Edge and Opera on a computer, Full screen also turns on the Keyboard Lock API, which lets the page receive Esc and, as far as the system allows, shortcuts such as Alt+Tab; hold Esc for two seconds to leave full screen.
key, code, location and keyCode
Each browser key event carries code — the physical key, named after the US layout (KeyA, Digit1, ShiftLeft), defined by the W3C UI Events KeyboardEvent code Values (Recommendation) — and key, the character or name it produces with your current layout and modifiers. location says which of two identical keys was used: 1 left, 2 right, 3 numeric keypad. keyCode is the old, deprecated number some scripts still read. The log shows all four, and it can be copied as tab-separated text.
Limitations
- The page can only see what the keyboard and the operating system pass to the browser; system shortcuts, Fn and some media keys may not arrive.
- Phone and tablet on-screen keyboards do not report physical keys; connect a hardware keyboard to test it.
- Keys that are not on the chosen layout (extra F-keys, media keys, Japanese keys) are listed below the keyboard instead of drawn.
- Results are kept only while the page is open.
Privacy
Everything happens in your browser. Key presses are shown on this page only; they are not stored, sent or recorded anywhere. Only your layout choices are remembered on this device.
Frequently asked questions
How do I test my keyboard online?
Press Start testing and press each key once. Keys that work turn green; the counter and the Not yet pressed list show which ones you still need to try. A key that never lights up is likely faulty.
Why does one key type two letters?
That is usually chatter: a worn or dirty switch bounces and sends a second press a few milliseconds after the first. The Chatter panel shows which keys do it and how quickly the second press came.
How many keys can my keyboard press at once?
Hold down more and more keys: Most at once shows the highest number the page received. Many basic USB keyboards stop at 6 normal keys plus modifiers; n-key rollover keyboards register them all.
Why don’t the Windows key, Fn or Print Screen light up?
Fn never sends a key to the computer. The Windows key, Print Screen and system shortcuts are often taken by the operating system first; in Chrome or Edge use Full screen, which lets the page capture more of them.
What is the difference between ANSI and ISO keyboards?
ANSI (US) keyboards have a wide, one-row Enter key and a long left Shift. ISO (UK and most of Europe) keyboards have a tall Enter key, a short left Shift with an extra key beside it, and the # key next to Enter.
Is what I type recorded?
No. Key presses are shown on this page and kept in memory only while it is open; nothing is uploaded or saved.