MouseTestHQ

Keyboard Tester & Anti-Ghosting Check

Click the test area first, then press any keys. They light up while held. Try the anti-ghosting test below to verify rollover.

Tip: Click anywhere on this page first so the keyboard receives input. Then press keys freely — including modifier combinations (Shift, Ctrl, Alt).
MAIN
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NUMPAD
Press any key to begin. Last 6 keys will appear here.

Anti-Ghosting / N-Key Rollover Test

Press the highlighted key combination simultaneously. The keys turn green if all are detected, red if any are dropped (ghosted).

Score: 0 / 0

About This Tester

This page listens to keyboard events globally and visualizes every key you press using event.code, which gives the physical key location regardless of your keyboard layout. That's how we can correctly distinguish left vs. right Shift or Numpad 1 from the number row 1.

What is Key Ghosting?

Most cheap keyboards use a 2KRO (2-key rollover) matrix or worse. This means pressing 3+ keys simultaneously can cause some inputs to be "ghosted" — the keyboard fails to register one or more presses. Modern gaming keyboards offer N-key rollover (NKRO), meaning every keypress is registered independently. The test above lets you verify your keyboard's actual behavior.

How the Anti-Ghosting Test Works

  1. Click "Next combo" to load a random combination of keys.
  2. Press and hold all the highlighted keys at the same time.
  3. If every key lights up green, your keyboard correctly registered all of them.
  4. If any key stays red, your keyboard ghosted that input.

Common Ghosting Patterns

  • WASD + Shift: The most common gaming failure — moving + sprinting simultaneously.
  • WASD + Space: Critical for FPS games — moving and jumping.
  • Modifier conflicts: Some boards fail when you press three modifiers at once (Ctrl+Shift+Alt).

Privacy

Keyboard events are processed entirely in your browser. We never log, transmit, or store what you type.

Keep testing

Best mechanical keyboard 2026Our full rankings, including which boards support true N-key rollover. Fix a stuck keyStep-by-step cleaning and switch replacement for sticky or ghosting keys.

Frequently asked questions

How do I test if my keyboard has ghosting?

Our keyboard tester runs an anti-ghosting rollover test automatically. Press the highlighted combinations on screen and the tool highlights exactly which keys your keyboard registers. If a key lights up that you are not pressing, that is ghosting. The tool also reports how many keys you can hold simultaneously, which is the N-key rollover count.

What is N-key rollover and how many do I need?

N-key rollover, or NKRO, means the keyboard registers every key you press simultaneously instead of blocking extra inputs once a limit is reached. Most cheap membrane and low-cost mechanical keyboards block at 3-6 keys, which is why gaming keyboards advertise rollover. For most typing and general use 6-key rollover is enough, but competitive games with many simultaneous bindings benefit from full NKRO.

Why does my keyboard register a key I did not press?

That is ghosting, and it comes from the keyboard's matrix design rather than a fault in your hardware. Cheap keyboards use a simplified matrix that cannot detect certain combinations without electrical crosstalk. A keyboard with proper N-key rollover avoids this entirely. Our mechanical keyboard guide covers which of our picks support full NKRO.

Can this keyboard tester detect a stuck key?

Yes. Press and hold any key and the tester marks it as active, and a key that stays highlighted after you release it is flagged as stuck. A stuck key usually means debris in the switch or a failing switch. Our keyboard cleaning guide has the step-by-step process for fixing it.

Does the keyboard tester work with laptop keyboards?

Yes. Laptop keyboards frequently have limited rollover and are a common source of ghosting problems, so the tester is particularly useful for confirming a problem. Note that some laptops have browser and OS shortcuts that intercept certain key combinations, which can produce a false ghosting result. Our 60% keyboard guide covers the alternatives.