Input Device Tests keyboard ghosting anti-ghosting

Keyboard Ghosting Test

Hold multiple keys to see which combinations register without ghosting.

Interactive tool

Run the test

Runs in your browser

Hold several keys at once. Chips show codes the browser received. If a previously held key drops when you add another, that is treated as ghosting suspicion (matrix conflict / limited rollover). A key you press that never appears while others are held is also ghosting. Watch the chip list as you type.

Peak simultaneous: 0

Press Start key capture to begin.

Permission status

Checked in your browser. DeviceHub does not store permission grants.

  • Special permission Not required

Live results

Metrics update as you run the test. Nothing is uploaded.

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Device information

Labels and capability details reported by your browser.

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Description

About Keyboard Ghosting Test

Introduction

Keyboard Ghosting Test shows which keys stay registered when you hold several at once. It surfaces matrix blocking and rollover limits the browser actually receives, including a clear peak simultaneous count.

What this tool does

It tracks keydown and keyup, highlights held keys, and reports the peak number of keys down together in the session. It does not flash firmware or certify electrical NKRO beyond what the OS delivers to the page.

When to use it

Use it for game chords, heavy editor shortcuts, and anti-ghosting claims. Run Keyboard Test first if single keys already fail. Retest after switching Bluetooth versus USB.

How it works

Pressed codes live in an in-memory set. Dropped members of a chord are ghosting or blocking as seen by KeyboardEvent traffic. USB boot protocol, hubs, and wireless modes can cap rollover even when marketing claims NKRO.

Step-by-step instructions

  1. Click the test surface so focus captures keys.
  2. Hold a real game or editor chord and watch for dropouts.
  3. Note the peak simultaneous count shown on the page.
  4. Retry on another port, cable, or wireless mode if results look odd.

Common problems

Dropped keys in large chords are often real rollover limits. Bluetooth usually underperforms wired USB. Remote desktop can filter dense chords. Sticky Keys can confuse held-state displays.

Privacy explanation

Chord tracking stays in your browser session. Avoid typing passwords while keys are highlighted. No special keyboard permission is requested.

Runtime principles

Built for the browser

What happens when you run this test — without downloads or accounts.

  1. 01

    Runs in your browser

    Keyboard Ghosting Test uses standard web APIs — no install, extension, or desktop app required.

  2. 02

    Reads what the browser allows

    Results come from events and capability signals the web platform exposes for this session.

  3. 03

    Private by default

    Input and diagnostic values stay in your browser session for display — nothing is sold as media.

Compatibility

Supported browsers

Expected support for modern engines. Individual APIs may still vary by device.

  • Chrome

    supported

    Latest stable

  • Firefox

    supported

    Latest stable

  • Safari

    supported

    Latest stable

  • Edge

    supported

    Latest stable

Devices

Supported devices

Hardware and form factors this browser test is designed to exercise.

  • Physical keyboards

    Best results with hardware keydown/keyup events.

  • Mice & trackballs

    Buttons, wheel, and pointer tracking in the page.

  • Trackpads

    Click and scroll events from laptop trackpads.

Privacy

Your data stays with you

Keyboard Ghosting Test is built privacy-first. Diagnostics run in your browser session whenever web APIs allow.

Read our privacy policy

Troubleshooting

Common problems

Quick fixes before you dig into FAQs.

Combinations drop keys unexpectedly
That often is matrix ghosting or OS/USB limits, not a page bug. Retest here, try another port or cable, and compare a second keyboard.
All keys seem fine until WASD plus modifiers
Hold game-like chords deliberately, watch which codes disappear, and note whether a different USB hub or wireless mode restores the missing key.
Results disagree with manufacturer NKRO claims
Browsers report what the OS delivers. BIOS, USB polling mode, Bluetooth, and HID report size can still limit simultaneous keys even when the switch matrix is capable.

FAQ

Frequently asked questions

Structured answers for users and FAQ rich results.

Browse FAQs
What is keyboard ghosting?
When a keyboard matrix or firmware cannot uniquely report every simultaneous press, so one or more held keys never appear in the event stream.
What is the peak simultaneous count?
The highest number of keys this page saw held down together in your session, based on browser key events.
Why do results disagree with NKRO marketing?
Browsers report what the OS delivers. USB mode, Bluetooth, hubs, and BIOS limits can still cap chords.
Is a permission required?
No. Focus the test surface and press keys. No special HID permission prompt is used.
Are keystrokes uploaded?
No. Tracking stays in your browser session for this diagnostic.

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Release notes

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