Free Keyboard NKRO Test for Rollover, Simultaneous Keys, and Ghosting Checks
Use this keyboard NKRO test to track how many keys the browser sees at once, inspect keydown/keyup order, identify repeats, and run guided multi-key chord challenges.
Run the live browser test
| Event | Key | Code | Repeat | Held count |
|---|
12 practical features in this keyboard nkro test
Live held-key set
Built into this page as an interactive or diagnostic capability, not just a static explanation.
Peak simultaneous-key count
Built into this page as an interactive or diagnostic capability, not just a static explanation.
Keydown counter
Built into this page as an interactive or diagnostic capability, not just a static explanation.
Keyup counter
Built into this page as an interactive or diagnostic capability, not just a static explanation.
Repeat-event counter
Built into this page as an interactive or diagnostic capability, not just a static explanation.
Modifier-state display
Built into this page as an interactive or diagnostic capability, not just a static explanation.
Key and code logging
Built into this page as an interactive or diagnostic capability, not just a static explanation.
3-key guided chord
Built into this page as an interactive or diagnostic capability, not just a static explanation.
6-key guided chord
Built into this page as an interactive or diagnostic capability, not just a static explanation.
10-key guided chord
Built into this page as an interactive or diagnostic capability, not just a static explanation.
Per-chord completion status
Built into this page as an interactive or diagnostic capability, not just a static explanation.
CSV export and local history
Built into this page as an interactive or diagnostic capability, not just a static explanation.
How to read the diagnostic signal
| Signal | Useful interpretation | Important limitation |
|---|---|---|
| Stable repeat result | More useful for comparison than a single isolated sample | Still depends on the current browser, OS, and device state |
| Large change after one controlled adjustment | Good clue that the changed variable matters | Correlation is not always proof of root cause |
| Missing or inconsistent browser event | Useful troubleshooting evidence | Does not electrically inspect hardware components |
| Exported session summary | Helps compare before/after changes | Only as good as the test conditions you record |
Worked example: run the same test twice, change one relevant setting, then repeat it. A consistent change across repeated runs is more informative than a single isolated number.
Six short lessons for better testing
Control one variable
Keep device settings, browser zoom, and test mode constant before comparing results.
Repeat the measurement
One run can be noisy. Repeat the same test and look for a stable pattern.
Separate browser from hardware
Browser events are useful diagnostics, but they do not expose every firmware or electrical detail.
Use the right metric
Choose timing, accuracy, count, support, or geometry metrics that match the problem you are investigating.
Record context
Save the device, connection type, relevant settings, and test condition with any result you compare later.
Interpret, do not overclaim
Treat the page as a practical diagnostic aid rather than a laboratory certification instrument.
Complete the diagnostic workflow
Three-question diagnostic quiz
Recent saved milestones on this device
Continue without a dead end
Free Keyboard NKRO Test for Rollover, Simultaneous Keys, and Ghosting Checks: FAQ
What is NKRO?+
N-key rollover describes a keyboard’s ability to report multiple simultaneous keys without losing intended presses.
What is keyboard ghosting?+
Ghosting is an unwanted or missing key behavior caused by how the keyboard matrix handles combinations. Browser tests can reveal reported keys but cannot inspect the electrical matrix directly.
Why do browser shortcuts interfere?+
Some operating-system and browser shortcuts are handled before the page can fully use them. Guided chords therefore favor ordinary letter keys.
Does seeing 10 keys prove true NKRO?+
It proves the tested combination reached the browser, not that every possible key combination supports unlimited rollover.
What does the repeat flag mean?+
When a key is held, browsers can emit repeated keydown events. Those repeats are counted separately from the initial press.
Use the result responsibly
This tool reports what a browser can observe or calculate in the current environment. Firmware, drivers, operating-system processing, permissions, transport, display timing, audio hardware, device design, and browser implementation can add behavior that this page cannot isolate.
External technical reference: MDN: KeyboardEvent ↗.