⭐ 0
🔍
Text Image PDF & Docs Audio Music Electronics Time Utilities Validators Esoteric Games

Key Rollover Test — NKRO & Ghosting Check

Press any key and watch it light up on an on-screen keyboard: check every switch, count simultaneous keys and spot dead or chattering keys.

EscF1F2F3F4F5F6F7F8F9F10F11F12
`1234567890-=⌫
TabQWERTYUIOP[]\
CapsASDFGHJKL;'Enter
ShiftZXCVBNM,./Shift
CtrlMetaAltAltMetaMenuCtrl
◀▲▼▶

0
0
0
0

Processing... 0%

Result

This page opens the keyboard tester with the simultaneous-keys counter highlighted: hold down more and more keys and watch how many actually register at once — the maximum reached stays on screen.

Rollover is how many keys a keyboard can report at the same time. Budget boards often manage only a few keys in some combinations and may "ghost" — register a key you never pressed — while gaming keyboards advertise 6-key rollover (6KRO) or full N-key rollover (NKRO). Try classic problem clusters like WASD plus Space and Shift.

One honest caveat: the browser and the operating system can cap how many simultaneous keys they pass through, especially in some USB modes. A low reading here proves nothing by itself — but a high one confirms your board, cable and OS all handle the combination fine.

🛡️
Executed in Browser

Your files and inputs never leave this device. Processing runs completely offline. 100% Secure.

Accepted Formats & Rules

  • On-screen ANSI keyboard that reacts to real keydown and keyup events via KeyboardEvent.code.
  • Press history line, total press counter and a dedicated spacebar counter.
  • Tab, Space, F-keys and quote keys are intercepted during the test so the browser does not hijack them.

Key Benefits

✓ Nothing to install: the tester runs entirely in your browser and starts the moment the page loads.
✓ Two-color feedback: keys that are held down light up one way, keys that have ever registered stay marked — so you always know which switches were already tested.
✓ Rollover insight: a live counter shows how many keys the browser reports as held at once and remembers the maximum reached.

Use Cases

  • • Check every key of a second-hand or repaired keyboard: walk across the rows and any key that never lights up is dead.
  • • Hold WASD plus Space and Shift to see how many keys your board registers at once before buying it for gaming.
  • • Verify a key you suspect of double-typing (chatter) by comparing the press history with the number of physical presses.