Rules & quick reference
| Start | Focus the keyboard test panel |
|---|---|
| Count | Distinct codes held between keydown and keyup |
| Exit | Tab moves focus out; releasing focus clears held state |
| Limit | OS-reserved combinations may never reach the browser |
Focus and press a combination
Click the test panel before pressing keys. The visual keyboard highlights codes currently held down and keeps a subdued indication of keys seen during the session. Held now counts distinct received codes. Maximum together records the largest simultaneous set observed, and Unique keys counts codes used at least once. Save maximum stores only that summary in local history. The visual key names describe a common physical-code layout rather than remapping every language’s printed keycaps.
Rollover depends on the combination
A keyboard matrix can handle one group of keys while blocking another. Test the specific combination your game or application uses, such as movement keys plus a modifier and another action. A large maximum on one combination does not prove unlimited rollover for every combination. Holding a key produces repeated keydown events on many systems; the test ignores repeat and uses a set of physical codes so that one held key is counted once.
Interpret missing or unexpected input
Ghosting can refer to phantom presses, while blocking and rollover limits concern missing simultaneous presses. This page displays events the browser receives and cannot independently determine what the hardware should have emitted. The operating system, an accessibility feature, firmware, a remote desktop or a browser shortcut can intercept a combination first. Some reserved shortcuts cannot be suppressed by a web page. A missing highlight therefore needs further checking rather than an immediate hardware diagnosis.
Leave the test without trapped keys
Tab keeps its ordinary navigation behavior so you can exit the panel using a keyboard. Moving focus away or losing window focus clears the held set, preventing a key released elsewhere from appearing stuck indefinitely. Function keys and media keys may invoke system behavior before the browser sees them. Use a calm sequence of simple combinations and note the exact physical keys involved. This tester keeps no text transcript: the session uses key codes, and saved results contain only the maximum simultaneous count.
Your result stays on this device
Completed game results are saved in this browser when local storage is available. Bests and recent history describe this device’s saved runs, not a public leaderboard. Changing browsers, clearing site data or using private browsing can remove them. Copy score writes only the visible result summary to your clipboard when you request it; sharing is your choice. Clear local game data removes scores, daily completion markers and the saved 2048 board for this origin. No game result is uploaded, and the games remain usable when persistent storage is unavailable. Use the rule table to check what the active mode measures before comparing another session. A changed duration, input method or grid difficulty can change the task even when the displayed score uses the same unit.
Frequently asked questions
Does a high maximum prove NKRO?
No. Test each relevant combination; a browser cannot certify every hardware matrix path.
Why are some shortcuts missing?
The OS, browser or firmware may intercept them before the page receives events.
How do I leave the test?
Press Tab or click elsewhere. Held state is cleared when the test loses focus.
Is my typed text saved?
No text transcript is stored. Saving records only the maximum simultaneous count.
Built by Mihai · Reviewed 2026-10-24 · Read the related technical guide · Testing policy