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Anti-Ghosting Test
Checks whether simultaneous key presses all arrive, and how many your board can hold at once.
- Available — Live on this site right now.
- Browser Tool — Runs in the browser you are reading this in.
- No Install — Nothing to download, no extension, no account.
- Client-Side — Runs entirely on your device. No test data is uploaded.
- Desktop — Needs a physical keyboard or mouse to be useful.
This page explains the tool. The tool itself is one click away and needs no sign-in.
Open Anti-Ghosting TestWhat is this tool?
Ghosting is when you hold several keys at once and one of them silently fails to register. On a cheap membrane keyboard, holding W and A and then pressing D can drop a key entirely — which in a game means you stop moving.
Rollover is the specification behind it: how many simultaneous keys the board guarantees. 2KRO handles two, 6KRO handles six, and NKRO handles every key at once.
This test asks you to hold a named combination and reports whether every expected key arrived. It also tracks the largest number of keys it ever saw held together, and lights up a tier ladder from 2-key up to NKRO as you clear each threshold.
How to use it
- Pick a combination setWASD covers the six movement combos, ending with all four at once. Gaming adds Shift and Space — sprint and jump while moving. Modifiers checks Ctrl+C, Ctrl+V, Ctrl+Shift+S and Alt+Shift. Custom lets you build your own.
- Press START TEST or Run TestThe current combination is shown as a heading, for example W + A. Hold every key in it at the same time.
- Hold, then release togetherPress them simultaneously rather than in sequence, and hold for a moment before releasing. The tool evaluates the set of keys that are down at the same instant.
- Move through the listNext Combo → advances. Clear Log empties the event list, Reset starts a fresh session with the tier ladder cleared.
- Push the ladder higherTo find your real ceiling, hold as many keys as you can at once. The maximum-simultaneous counter and the tier ladder record how far you got.
What the results mean
A pass
Every key in the combination was down at the same time and all of them reached the browser. That combination is safe on your keyboard.
A missing key
One or more expected keys never arrived while the others were held. That is the ghosting symptom — and it is exactly what costs you a movement input mid-fight.
The rollover ladder
Tiers light up as you reach them: 2-key at two simultaneous, then 3, 4, 5, 6, 8-key, and NKRO once ten or more keys register together. Ten is the practical threshold used here; a board that clears it is behaving as full n-key rollover for any realistic use.
Modifier combinations behaving differently
Ctrl and Alt combinations can be intercepted by the operating system or the browser before the page sees them. A modifier combo that fails while WASD passes is more likely a reserved shortcut than a rollover limit.
What it can detect
- Keys that drop out when several are held together
- The largest number of keys your board delivers simultaneously
- Which rollover tier your keyboard behaves like, from 2-key to NKRO
- Combinations that fail specifically because a modifier is involved
Limits worth knowing
A browser can only report what the platform gives it. These are the honest boundaries of this page, so a result is never read as more than it is.
- A failure here does not prove hardware ghosting. The result is what survived the keyboard, its cable or receiver, the operating system and the browser — any of those can drop a key.
- The test cannot read your keyboard's rollover specification from its firmware. It measures observed behaviour, which is the thing that actually affects you but is not the same as the datasheet.
- Combinations the operating system reserves may never arrive at all, and that is not a keyboard fault.
Tips
- Test the combinations you actually use. Passing W+A+S+D matters far more than clearing an eight-key ladder you will never press.
- USB keyboards in boot-protocol mode are limited to six keys plus modifiers. If you stall exactly at six, that is the likely reason rather than a defect.
- If a wireless board fails a combo that its wired mode passes, suspect the receiver or a low battery before the switches.
Troubleshooting
W + A + S + D fails on my laptop
Laptop keyboards are usually membrane with limited rollover, and this is a common result. It is a design limit rather than a fault.
Ctrl + Shift + S does nothing
An application or the browser is claiming it. Try the same combination from the WASD set to confirm the keys themselves register together.
The tier ladder stops at 6-key
Six simultaneous keys plus modifiers is the USB boot-protocol limit. Many keyboards need NKRO enabled explicitly, often through a firmware toggle or a key combination.
My keyboard advertises NKRO but the test says otherwise
Check whether NKRO is switched on — plenty of boards ship in 6KRO mode for BIOS compatibility. Also confirm you are on a direct USB port rather than through a hub or a KVM.
Ready to run it?
Checks whether simultaneous key presses all arrive, and how many your board can hold at once. Nothing to install, and it opens in this browser.