Input Lab Keyboard

Key Rollover Test

Test keyboard rollover and ghosting with a live held-key map, maximum simultaneous key count, NKRO guidance and a local history of delivered key combinations.

Runs locally No account Repeat freely
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Key Rollover Test Guide

How to use the key rollover test

Hold increasingly large key combinations over the tester. The virtual layout highlights every code the browser reports and records the largest simultaneous set.

Understanding the results

Max at once is the delivered rollover result for the combinations you tried. A missing key in one specific chord can indicate matrix blocking or ghosting prevention.

What this browser tool can measure

Operating-system shortcuts and keys such as Fn may be intercepted before reaching a web page. Test several combinations because rollover can vary across the keyboard matrix.

Private by design

The interactive work happens locally in this browser. No account is required, and test inputs are not sent away to calculate the result.