Key Rollover Test
Watch the number of simultaneously held keys and the highest combination your browser has received in this session.
Activate the test, then press keys on your keyboard.
Held keys are cleared when the window loses focus.
No keys held
These results show only events delivered by your browser and operating system. They cannot certify N-key rollover or identify every hardware ghosting issue.
Use a physical keyboard. On a phone or tablet, connect an external keyboard to test hardware keys.
How to use this tool
- Choose the layout that matches your physical keyboard and activate the test.
- Press and release each key, or hold a combination. Filled keys are held; a check mark means tested.
- Restart to clear tested keys and the peak count. Held keys clear automatically on blur.
What this test can tell you
These results show only events delivered by your browser and operating system. They cannot certify N-key rollover or identify every hardware ghosting issue.
Fn, power, and system shortcuts may not reach this page. A missing event does not prove a faulty key.
Good questions. Clear answers.
Does a high count prove N-key rollover?+
No. The peak is the largest event set observed on this page, not a certified keyboard specification. Try different combinations, and consult the manufacturer for hardware guarantees.