About the Keyboard Tester
This keyboard tester shows every signal your browser receives from the keyboard on a full-size 104-key layout, so you can spot dead or faulty keys in seconds. Use it to check a new keyboard, find out which keys stopped working after a spill, or see whether a gaming keyboard really supports N-key rollover.
Every key that registers once stays green, so press through the whole keyboard and any key still white is the one to look at.
How to use
- Open this page on a computer and press the keys on your keyboard one at a time.
- Keys turn blue while held and green once they have registered. A key that stays white may be faulty.
- Hold several keys together to see how many are recognized at once under Max at once.
- Check the Key log for keys that type twice from a single press (chattering), and press Reset to start over.
What is key rollover?
Rollover is the number of keys a keyboard can register at the same time. Many office keyboards only handle 2–3 keys in certain combinations (2KRO/3KRO), while gaming keyboards support 6 keys (6KRO) or every key (NKRO, N-key rollover).
Hold a gaming combo such as W + A + Shift + Space. If Keys held now shows fewer keys than you are pressing, that combination is blocked (ghosting/jamming). Note that USB keyboards in boot/BIOS-compatible mode are limited to 6 keys.
When a key seems broken
- No response at all: pull the keycap, clean out debris and test again. On mechanical keyboards the switch can often be replaced.
- One press, two characters (chattering): if the key log shows the same key twice in a row, the switch contacts are worn. Raise the debounce time in the maker's software or contact support.
- Fn key: it is handled inside the keyboard and never sends a signal to the computer, so it is normal that it doesn't light up.
- Laptops: missing keys such as Insert or the numpad are simply not on the keyboard; F-keys may need Fn held down.
FAQ
Can I test my keyboard on a phone?
Not the on-screen keyboard, because it doesn't send key positions. A physical keyboard connected by Bluetooth or USB (OTG) can be tested.
Pressing the Windows key or Print Screen opens something else.
The operating system intercepts some keys before the browser sees them, so they may arrive late or not at all. Print Screen usually only shows up when you release it — that is normal.
Does it work with a Mac keyboard?
Yes. ⌘ Command appears on the Win key and ⌥ Option on Alt. On a Mac, keys pressed while ⌘ is held don't send a release signal, so they are released together when you let go of ⌘.
Will shortcuts like Ctrl+W close the tab?
Shortcuts with Ctrl or ⌘ are not blocked, so the browser may close or reload the tab. Test combinations with Shift and Alt instead.
My keyboard uses a different layout. Does that matter?
No. Keys are detected by their physical position, so AZERTY, QWERTZ, Dvorak and other layouts are tested correctly — only the printed labels may differ.