Keyboard Ghosting Test
See how many keys your keyboard registers at once. Click the keyboard below and hold down several keys together — every key it registers lights up.
Click the keyboard so Space and arrows test here instead of scrolling the page, then press and hold several keys at once — press Tab or click away to exit.
Press and hold several keys at once — try W + A + Shift + Space.
Test real combos
Hold the combos you actually use — W + A + Shift + Space for games, or a full row of letters.
Screen vs fingers
A held key that stays dark is blocked; a key that lights up untouched is a ghost.
Stuck at six?
Six keys plus modifiers is the USB default — many gaming boards need an NKRO toggle to go higher.
Most keyboards read their keys through a grid of rows and columns rather than a dedicated wire per key. Hold several keys that share rows and columns and the controller can misread a fourth key you never pressed — a ghost — or, to avoid that, silently drop the extra key. Either way a keystroke is lost, which is why holding W + A + Shift to strafe can leave Space unable to jump, and why fast typists sometimes drop letters when keystrokes overlap.
This test lights up every key your keyboard actually delivers to the browser. Hold the combinations you care about and compare the screen against your fingers — the most keys you can register at once is your effective rollover. A key that never registers even on its own is a hardware fault, not ghosting; the Keyboard Tester finds those.
Ghosting, blocking and rollover
- Ghosting — a key you never pressed registers, because the matrix cannot tell some combinations apart. The worst case: it adds input you did not make.
- Blocking (anti-ghosting) — the keyboard drops the extra key instead of guessing. Safer than ghosting, but the keypress is still lost.
- Rollover — how many keys register at once. 6KRO means six plus modifiers; N-key rollover (NKRO) senses every key independently, so nothing is dropped.
Reading your maximum
| Max keys at once | What it means |
|---|---|
| 2–5 | Limited rollover — typical of basic membrane keyboards; blocking will show up in games |
| 6 | 6-key rollover, the classic USB standard — plenty for typing and most gaming |
| 7–9 | Strong anti-ghosting — the board resolves most combinations that trip up cheaper keyboards |
| 10+ | Effectively N-key rollover — every key is read independently |
Browser and hardware notes
- The browser only sees what the OS passes on, so the count is your effective rollover for the whole chain — keyboard, USB mode, OS and browser — not the switch matrix alone.
- Many keyboards ship in 6-key USB mode and need an NKRO toggle or driver setting to go higher — check the manual if a gaming board caps at six.
- Modifiers (Shift, Ctrl, Alt) usually stack on top of the six, while a few OS or browser shortcuts (screenshots, window switching) stay reserved no matter the keyboard.