Device BenchDevice test · Input
Keyboard Tester
Press a key and watch for its event on the diagram or in the extra-keys list. Use the rollover test to compare simultaneous key counts, or try three-key combinations in the ghosting matrix. No download is needed, and nothing you type leaves your browser.
- untested
- registered at least once
- reported held
- not measured here
Tab, Enter and Space are being tested instead of operating page controls. Press Escape to use Tab for navigation.
Key rollover / NKRO test
Hold several keys together, then add another. Max rollover records the largest set of keys this page tracked as held; Non-mod peak leaves out Shift, Ctrl, Alt and the OS keys. Try the combinations you use in games or shortcuts as well as a larger spread.
Hold several non-modifier keys, such as letters, to start the rollover check.
Most keys reported at once: —
Modifiers in that set: none
Most non-modifier keys reported at once: —
These counts describe the events that reached this page, not the keys under your fingers. A high count does not establish NKRO, and a plateau does not identify the keyboard's limit or the cause of a missing event.
Keyboard ghosting test
Hold each three-key combination below for about a second. Watch "Reported now": a row records "all 3 reported" when the page tracks all three together. If you held the whole combination but a key did not appear, release it and choose "Held all 3 — report blocked" for that row.
| Combination | Reported now | Result | If a key never arrives |
|---|
No combination run yet.
A missing event does not show why a key failed to appear. "Blocked" is your report that you held all three; the row also shows the largest subset the page recorded together.
What this test cannot see
An untested key means no matching event has reached this page. The event may have been intercepted, may be unsupported, or may never have been sent. Some shortcuts can also switch tabs or take you away from the test.
- Fn — often handled by the keyboard itself without a separate event reaching the page. Its diagram cell stays hatched.
- System chords — Alt+Tab, Command+Tab, Command+Space and OS-key shortcuts can be claimed by the operating system before this page receives them.
- Ctrl and Command shortcuts — the page does not suppress these, so reload, developer tools and tab shortcuts can still run. Events that reach the page can still appear in the readouts.
- Media-mode F rows — some keyboards send media events when you press an F-row key. Try F-Lock or Fn if you meant to test F1–F12. Unmapped codes appear in the extra-keys list.
How this test works
The tester listens for keydown events and marks keys as released when it receives a release event. The event's code reports a key position; key gives the character or action reported for your layout. The diagram uses code with US labels, so an AZERTY A can light the Q position while the Key readout shows the character typed. Codes outside this reference layout appear in the extra-keys list.
The classic USB boot-keyboard report has six ordinary key slots and separate bits for modifiers. That is why the page keeps a non-modifier peak as well as the all-key peak. Each peak stores its own set of keys, since the two records may come from different moments. The browser does not expose the underlying report format here, and one successful set does not show that every other combination will work.
The guided combinations use nearby keys and common game controls, not a map of your keyboard's internal wiring. They omit Ctrl, Alt and OS keys to avoid common system shortcuts. A row records "all 3 reported" as soon as all three are tracked together. If you report a blocked combination, the row keeps that report beside the largest subset recorded so far. A later attempt that registers all three replaces it with "all 3 reported".