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Device tests · Input Devices

Keyboard Ghosting & Key Rollover Test

Hold gaming or typing combinations together to see which physical-key events your browser receives at the same time. Compare Sprint + Jump, WASD, FPS, MOBA and rhythm presets, or use a free combination.

This keyboard ghosting test observes delivered events. It cannot electronically inspect a keyboard matrix or certify NKRO. Do not type passwords or other sensitive text.

  • Local observations
  • No hardware certification

Do not type passwords or sensitive text. Browser and system shortcuts still apply.

Ready to test combinations

Free mode: hold any deliberate combination.

    Browser-observed rollover

    Held now
    0
    Maximum observed
    0
    Preset together
    0 / Free
    Modifiers
    None

    Browser observed at least 0 simultaneous keys during this run. This does not certify NKRO.

    Your result

    What your result means

    The maximum is the largest simultaneous held-key set observed after Start. It shows a lower bound: this browser observed at least that many keys together. Repeated keydown events for a held key do not inflate the count.

    Preset observed / expected shows the strongest single simultaneous attempt, not a union of keys pressed at different times. An expected key not present in that attempt is a possible missing observation, not a confirmed defective key. Use the exact left-side modifier labels for the supplied presets.

    People often call missing keys ghosting. Strictly, blocking is suppression of a key to avoid an ambiguous matrix state, rollover describes how many keys can be reported together, and phantom ghost input is an extra key that was not pressed. The browser sees only what survives device, OS and application handling.

    Procedure

    How the test works

    1. 01

      Choose a combination

      Select a preset matching a real task. Sprint + Jump uses W, left Shift and Space; WASD Stress adds A, S and D. Free Test Mode has no expected-key list.

    2. 02

      Start and focus

      Press Start Rollover Test. Events are observed only while the combination area has focus. Click it again if another control takes focus.

    3. 03

      Hold together

      Press and hold the expected keys simultaneously. Watch held keys, physical codes, produced keys and modifier state. Release fully between attempts.

    4. 04

      Compare attempts

      Try a missed combination again slowly, then change one key. Do not infer a specification from an isolated run or by pressing all expected keys one at a time.

    5. 05

      Keep navigation available

      Tab can leave the test area and Escape stops listening. Browser and system shortcuts are not all preventable; avoid combinations that close tabs or change applications.

    6. 06

      Finish and clear

      Stop clears held state. Blur and visibility changes also clear held keys so a lost keyup event does not leave a false held result.

    Methodology

    How Testpartout measures this

    This implementation uses browser observations and local calculations, with no hardware certification.

    What the implementation does

    • Held state is keyed by physical event.code where available, with event.key as the fallback identifier. A new keydown replaces the same identifier rather than adding a repeat.
    • Keyup removes the matching key. The maximum is updated only from the current held set.
    • Each preset is compared against the held set; the strongest simultaneous matching set is retained for the attempt summary.
    • The page displays event.key alongside code and the current Shift, Ctrl, Alt and Meta modifier flags.
    • Listening is limited to the focused test area and removed on Stop or route exit. Blur and visibility changes discard stale held state.

    Limits of a browser measurement

    • The OS, browser, keyboard firmware and layout can suppress or remap events before the page sees them.
    • Fn and some media keys may be handled inside the keyboard and may never produce an ordinary browser key event.
    • A large observed simultaneous count does not establish unrestricted n-key rollover for all combinations, interfaces or applications.

    Privacy

    What happens to your data

    This section describes the behaviour of the code on this page, not an intention.

    • Diagnostic events, coordinates, timings and observations stay in current page memory. They are not uploaded or saved as raw diagnostic data.
    • No camera, microphone, account or server storage is used by this test.
    • Only start and complete lifecycle events may be sent after analytics consent; no result values are included.

    Troubleshooting

    If the test does not behave as expected

    Blocking versus phantom input

    A missing event can be blocking or a reserved shortcut; an extra event can be remapping or another input source. Compare a deliberate single combination in a plain app before assigning a matrix explanation.

    6KRO and NKRO

    6KRO usually refers to six non-modifier keys reported together in a particular mode; modifiers may be handled separately. NKRO is a broader capability claim whose behavior depends on connection and firmware. This page counts all delivered held identifiers including modifiers and cannot certify either label.

    Gaming presets

    Use combinations you genuinely hold while playing. A keyboard may accept one six-key group but not another. Different matrix wiring or firmware handling can make group-specific behavior more important than a single maximum.

    Factors

    Interpret observations in context

    Reserved shortcuts

    Ctrl, Meta, Alt, Tab and function-key combinations can invoke browser or OS commands. A lost event in these combinations is not reliable evidence of a keyboard defect.

    Layouts and produced characters

    Code identifies a physical-position convention; key describes the produced value, affected by layout and modifiers. The preset uses codes, so an unfamiliar layout can show a different character while the expected code is present.

    USB and wireless modes

    Connection mode, hubs, firmware options and power state can alter reported combinations. Compare supported modes one at a time and consult the manufacturer’s documentation rather than changing firmware based on this page alone.

    FAQ

    Frequently asked questions

    Does this tool certify NKRO?
    No. It establishes only the maximum simultaneous held keys delivered to this browser during your attempts, not every possible combination or electronic capability.
    Why does ghosting sometimes mean missing keys?
    The word is used loosely. Blocking or rollover limits can drop keys; strict ghosting refers to phantom keys. This tool shows browser observations rather than assigning a matrix diagnosis.
    Do repeat events increase the maximum?
    No. Each physical code is represented once until release, so holding a repeating letter cannot inflate simultaneous count.
    Why does Fn not appear?
    Many keyboards process Fn internally without sending a standard event to the operating system or browser.
    Why are some preset keys missing?
    Confirm simultaneous presses, the correct left-side modifiers and test focus. Browser or OS shortcuts, firmware and hardware can all affect delivery.
    Are combinations recorded online?
    No. Keys, codes, combinations and counts stay in page memory. Only consent-controlled start and complete lifecycle events may be sent.

    Found an issue with this test? Report it.