Keyboard Test
Press keys and watch them light up - anything still unlit at the end is a key that is not registering.
This looks like a touch device with no physical keyboard. Connect a keyboard, or open this page on a desktop or laptop, to run the test.
Click this panel, then press every key you want to test.
A key listed here has either not been pressed yet, or is not registering at all. Press each one; whatever is still listed at the end is a dead key.
Newest first. A key that appears twice from one press is repeating; a key you pressed that never shows up here never reached the browser at all.
Some combinations are taken by the operating system before any web page sees them, so they cannot be tested here: Ctrl + Alt + Delete · Alt + Tab / Cmd + Tab · Alt + F4 / Cmd + Q · The Windows or Command key on its own · F11 and F12 in some browsers · Screen-capture and OS media keys. A key that fails here but works elsewhere is usually one of these, not a fault.
What this tool does
A keyboard test reports which keys your computer actually receives. Press every key in turn; any that stays unmarked is either untested or genuinely dead. It also measures how many keys register when held together, which is what ghosting and n-key rollover describe.
Highlights each key on an on-screen layout as you press it, and keeps registered keys tinted so the map doubles as a coverage chart. Keys that never registered are listed explicitly rather than left for you to spot.
Shows the code, key value and keycode for each press, which makes a layout mismatch visible - if pressing @ reports Quote, your system layout does not match your physical keyboard.
How to use it
- Click the test panel so it has keyboard focus.
- Pick which keys should count - the whole layout, or just the letters, number row, function row or modifiers. A laptop with no function row should not be told it has twelve dead keys.
- Press every key in turn. The coverage bar fills as you go, and recently pressed keys appear as tiles so a repeating key is visible.
- Check the tiles listed as not yet registered - after a full pass, anything remaining is a dead key.
- Hold several keys at once to test rollover, then copy the report if you need it for a warranty claim.
Why use this tester
A key that does not register is easy to miss until you need it. Pressing every key and seeing which stay unlit finds faults quickly, whether you are buying, repairing or setting up a keyboard.
Why we built it
We built the keyboard test to list the keys that never registered, which is the real diagnosis for a dead key. Look up key values with the key code finder and try switch sounds with the mechanical keyboard simulator.
For a neighbouring job there is also the Dead Pixel Test and the Gamepad Tester.
Who this tool is for
- People checking a new or damaged keyboard
- Gamers testing key rollover
- Repair technicians
When to use it
- Checking a new or second-hand keyboard.
- Diagnosing a sticky or dead key.
- Testing after cleaning or repair.
- Seeing key codes for development.
Dead keys and what causes them
The useful output is the list of keys that never registered. Pressing every key and watching squares light up tells you what works; what you actually came to find out is which key is dead, and that is a question about the keys you did NOT manage to trigger. So this lists them explicitly rather than leaving you to spot the gap — that listing is the real diagnostic job, and it is what most people came for.
A dead key is one that produces no event at all. On a membrane keyboard this usually means a worn or contaminated contact on the rubber dome; on a mechanical board it is normally a failed switch or a broken solder joint.
Test the key in this tool rather than in a text field. A key can appear dead in a document while registering perfectly here, which points at software - a stuck modifier, an input method, or an application shortcut swallowing it - rather than hardware.
If a key registers here but not in one particular application, the keyboard is fine. If it fails to register here as well, and cleaning under the keycap does not fix it, the fault is physical.
Some keys are intercepted by the operating system before any web page sees them, so they cannot be tested in a browser at all. A key that appears dead here but works normally elsewhere is almost certainly one of those.
Ghosting and n-key rollover
Keyboards wire their keys as a grid rather than running an individual line to each one, which keeps costs and cabling down. The consequence is that certain combinations become ambiguous: three keys forming a rectangle on the grid can make the controller register a phantom fourth. That phantom is ghosting.
Most modern keyboards prevent phantom keys with diodes, but many still limit how many keys they will report simultaneously. Six-key rollover, or 6KRO, is the common limit and is what the USB HID specification guarantees. N-key rollover, or NKRO, means every key can be reported at once.
Hold as many keys as you can and watch the held-at-once figure. Six is normal and fine for typing and most games. Reaching ten or more indicates NKRO. Stalling at two or three in specific combinations suggests a matrix limitation that will show up in games using several simultaneous inputs.
| Level | Simultaneous keys | Typical of |
|---|---|---|
| 2KRO | 2 plus modifiers | Basic membrane keyboards |
| 6KRO | 6 plus modifiers | Most keyboards over USB - the HID standard |
| NKRO | Every key | Gaming and enthusiast mechanical boards |
Reading the key data
Each press reports three things. The code is the physical position on the keyboard and does not change with layout - the key right of Tab is always KeyQ, even on an AZERTY board where it prints A. The key is the character produced, which does depend on layout and modifiers. The keyCode is a legacy number kept for compatibility.
This distinction is the quickest way to diagnose a layout mismatch. If pressing the key marked @ reports a key of " and a code of Quote, your operating system is set to a different layout than the keyboard you are typing on - a US layout on a UK board, or the reverse.
Location distinguishes duplicated keys: 0 for standard, 1 for left-hand modifiers, 2 for right-hand, 3 for the numeric keypad. It is how left Shift is told apart from right Shift when both report the same key value.
What you give it, and what you get back
| Item | Details |
|---|---|
| Input | Press every key. |
| Output | A key map that lights up as keys register and a list of keys not pressed. |
| Details | Key and code values for each press. |
Issues you may run into
| What you see | Why it happens | What to do |
|---|---|---|
| A combination does nothing | The operating system reserves some shortcuts. | Test those keys individually. |
| The layout does not match mine | The map is a standard 60% ANSI layout. | Use the key list instead. |
| A key shows twice or not at all | Chatter or a dead switch. | Clean it or replace the switch. |
Assumptions and limitations
- Combinations reserved by the operating system cannot be captured by any web page. Ctrl+Alt+Delete, Alt+Tab, Alt+F4 and the Windows or Command key alone are the common ones.
- The on-screen layout is a standard 60% ANSI arrangement. Numeric keypads, media keys and ISO-specific keys are not drawn, though they still register and appear in the last-key panel.
- Rollover results are limited by the connection as well as the keyboard. A keyboard capable of NKRO may report only 6KRO through some USB hubs or KVM switches.
- The test shows what your browser receives. It cannot distinguish a keyboard fault from a cable, port, or driver problem.
- Touch devices with no physical keyboard cannot run this test.
Frequently asked questions
How do I test if my keyboard keys work?
Click the test panel to give it focus, then press every key in turn. Each key that registers is highlighted and stays tinted. After a full pass, anything still listed as unregistered is a dead key - assuming it is not one of the combinations the operating system reserves.
What is keyboard ghosting?
Ghosting is when a keyboard reports a key you did not press, caused by ambiguity in the grid the keys are wired into. Three keys forming a rectangle on that grid can make the controller infer a phantom fourth. Most modern keyboards prevent it with diodes.
What is n-key rollover?
N-key rollover means every key can be registered simultaneously, however many you hold. The common alternative is 6KRO, which reports six keys plus modifiers and is what the USB HID standard guarantees. NKRO matters mainly for games needing several inputs at once.
Why are some of my keys not working?
Test them here first. If a key registers in this test but not in a particular application, the keyboard is fine and something in software is intercepting it. If it fails to register here too, and cleaning under the keycap does not help, the switch or contact has most likely failed.
Why will some key combinations not register in the test?
The operating system claims certain combinations before any web page sees them - Ctrl+Alt+Delete, Alt+Tab, Alt+F4, the Windows or Command key alone. No browser-based test can capture these. It is a limitation of the platform, not a fault in your keyboard.
What is the difference between a keycode and a scancode?
The code reports the physical key position and never changes with layout, so the key right of Tab is always KeyQ. The key reports the character actually produced, which depends on your layout and modifiers. If they disagree with the printing on your keycaps, your system layout does not match your hardware.
Further reading
Why your keyboard sometimes drops a key when you press several at once — Press three keys at once on the wrong keyboard and a fourth key can silently appear, or a real one can vanish. Both come from how it is wired.