Keyboard Tester
Press every key. Held keys glow, keys that have worked stay marked, and the rollover counter shows how many keys your keyboard can register at once.
Needs a physical keyboard. Tip: hold W, A, S, D, Shift and Space together to check your gaming combo.
Rollover and ghosting, briefly
Cheap keyboards wire keys in a grid and read it row by row. Press three keys that form the corners of a rectangle in that grid and the fourth corner can appear to be pressed too: that is ghosting. To avoid it, manufacturers block some combinations instead, which is why a key sometimes does nothing while others are held.
Keyboards with a diode on each switch can read every key independently, called N-key rollover (NKRO). USB keyboards in basic "boot" mode are limited to 6 keys plus modifiers, so a 6 or 7 result can be a protocol limit rather than a fault.
Checks worth doing
- Every key once: any dark key after that is dead or remapped.
- Your movement combo held together, plus jump and sprint.
- The spacebar speed test for a sticky or dropping spacebar.
- Fast repeated taps on one key: if the tested count jumps unexpectedly, the switch may chatter.
Questions
How do I test my keyboard?
Press every key once. Each key lights up while held and stays marked after it has registered, so any key that stays dark is not being detected.
What is key rollover?
Rollover is how many keys a keyboard can register at the same time. Hold down as many keys as you can: the "most keys at once" counter shows the highest number detected together. Many office keyboards manage 6 or fewer; gaming keyboards often advertise N-key rollover.
What is ghosting?
Ghosting is when pressing certain combinations makes a key you did not press appear, or blocks a key you did press. Hold the combination you use in-game (for example W, A, Shift and Space) and check that exactly those keys light up.
Why do some keys like F5 still work?
The page blocks most keys from doing their usual job while testing, but leaves refresh and developer shortcuts alone. Browser and system shortcuts like Alt+Tab or the Windows key cannot be intercepted.