Keyboard Ghosting Test
An anti-ghosting and keyboard rollover test: hold a combination of keys at once and see whether every key registers. Presets cover common gaming combinations; any keys you hold are counted too. The page shows the most keys received at once and which keys drop out of a combination. It shows what your browser received, not a certified rollover (NKRO) rating.
1. Test
Press each key once. Green means your browser received it. Striped keys (like Fn) never reach a browser, so they are not counted. When you are done, press I've pressed every key so anything missing is reported.
While the test runs, keys do nothing else on this page. Stop with the button, or hold Escape for two seconds.
Advanced
Last events, as your browser delivered them (shown live, never saved):
| type | key | code | location | repeat | modifiers | time (ms) |
|---|
2. Result
Is it the keyboard or the computer?
Save the JSON here, run the test again with the keyboard on another computer or USB port, then load the first file. If the same problem shows up on both, it follows the keyboard.
In this browser
About the Keyboard Ghosting Test
How to use it
- Press Start test. The Combinations tab is already open.
- Hold every key of a preset at the same time, pressing them one after another and keeping them all down.
- Watch the preset line: every key should show as held. A key listed as missing dropped out of that combination.
- Try the combinations from your own games too; the most keys held at once is counted from anything you press.
What this page focuses on
- Preset combinations (W+A+Shift+Space, Q+W+E, Ctrl+arrow keys, home-row six) show which key drops out when one does.
- Counts the most keys held at once, from any keys you press, not only the presets.
- Separates a missing key in a combination (blocking) from a key that never works at all.
- States plainly that a browser count is not a rollover certificate: the operating system and USB mode can cap the number of keys a page sees.
Reading your result
- All keys received: Every key in the combination arrived together. That combination is safe for games.
- A key missing: The keyboard blocked that key while the others were held. Budget keyboards often block particular combinations because of how their keys are wired.
- Most keys at once: The largest number of keys the browser saw held together. It proves at least that many work together; it cannot prove more are impossible.
What is keyboard ghosting?
Strictly, ghosting is a key registering that you did not press. Most keyboards today block instead: when too many keys are held, the extra key simply does not register. Both show up here as a combination that does not match what you held.
Can this test NKRO (n-key rollover)?
Not definitively. Browsers and operating systems can limit how many simultaneous keys a page receives, so a lower count here does not prove the keyboard is limited. A higher count does prove at least that many keys work together.
Only some combinations fail. Is that normal?
Yes, on many budget keyboards. Keys that share wiring block each other in particular combinations. If a combination you use in games fails, remap the keys or use a keyboard with anti-ghosting.
What a browser cannot test
Fn is handled inside the keyboard and never reaches any web page. Brightness, volume and media keys are often taken by your system first. Browser and system shortcuts (Ctrl+W, Alt+Tab, the Windows key) are kept by the browser or system, except in Full keyboard mode in Chrome and Edge. Ctrl+Alt+Delete cannot be tested anywhere. No web page can measure keyboard latency, scan rate or polling rate, or certify a rollover (NKRO) rating, and this one never claims to.
Privacy
The test runs entirely in your browser. Nothing you press is uploaded, and nothing is saved after you close or refresh the page. Saved files are created on your device and only go where you send them.