Keyboard Rollover Test — Check NKRO & Ghosting

Hold several keys at the same time to see what the browser receives. Test common gaming combinations, record your maximum simultaneous key count and look for keys that disappear when a particular combination is held.

FreeNo installNo accountLocal-firstMobile-aware

LIVE DIAGNOSTIC

Rollover & gaming-combo test

Focus the panel, choose a preset combination or use your own keys, then hold them together for a moment.

Input stays in this page

Ready.

WHAT IT CHECKS

What the rollover test measures

Keys currently held at the same time
Maximum simultaneous keys observed in this session
Expected versus observed keys for gaming presets
Possible missing keys while a preset is held
Physical key codes rather than typed characters

READ THE RESULT

How to interpret the result

2KRO, 6KRO and NKRO describe how many simultaneous keys a keyboard can report under specified conditions. Ghosting/blocking behavior can depend on the exact key matrix and connection mode. For gaming, test the combinations you actually use rather than relying only on a maximum number.

QUICK WORKFLOW

How to use this test

Use repeatable conditions. One browser result is a diagnostic clue, not a complete hardware verdict.

Choose a preset

Try movement combinations such as W + A + Shift + Space, or test your own in-game bind.

Focus the capture area

Click inside the test panel so keyboard events reach the page.

Hold the whole combination

Press and hold all expected keys together instead of tapping them one by one.

Repeat different combinations

Keyboard matrix limits can be combination-specific, so one successful group does not prove every group will behave the same.

METHOD & LIMITATIONS

What the browser can — and cannot — tell you

The page only knows which KeyboardEvents reach the browser. It cannot see electrical matrix activity that the keyboard firmware blocks before the operating system. Browser or OS shortcuts can also intercept combinations, so treat missing keys as a clue to verify in another environment.

Technical reference: MDN — KeyboardEvent.code ↗

HELP

Common questions

What is NKRO?

N-key rollover means the keyboard is designed to report many simultaneous key presses without dropping legitimate keys. Real behavior can still depend on connection mode, firmware and the exact key combination.

What is keyboard ghosting?

Ghosting is unwanted or missing key behavior caused by how a keyboard matrix handles simultaneous presses. Modern keyboards often use blocking or anti-ghosting designs to avoid false extra keys.

Why does one gaming combo fail but another works?

Rollover limits can be matrix-specific. Two combinations with the same number of keys may travel through different electrical paths and behave differently.

Does a browser result prove the keyboard specification?

No. It shows what this browser received under this setup. Use it to test the combinations that matter to you and compare another device/browser when results are surprising.