⌨️ Keyboard Tester
Press keys to test your keyboard online: every key lights up on a full layout, with key codes, rollover (keys held at once) and key-chatter detection.
Press every key on your keyboard. Keys turn green once they register and blue while held. Hold several keys at once to test rollover.
No key chatter detected. Chatter is flagged when a key registers again within 40 ms of being released.
The Windows key, Fn, and some media keys are handled by the operating system and may not reach a web page, so they can stay unlit even when they work.
What Keyboard Tester Does
This keyboard tester shows a full-size layout on screen and lights up each key the moment your browser receives it: blue while it is held down, green once it has registered at least once. Work across the board row by row and any key that stays gray is a key the computer never saw — a dead switch, a stuck membrane, or a key your operating system is intercepting.
Two problems that a simple “does it light up” test misses are reported separately. Rollover is how many keys the keyboard can report at once; the tester records the highest number held simultaneously, which matters for gaming and fast typing. Chatter is a worn or dirty switch sending two presses for one — the tester flags any key that registers again within 40 milliseconds of being released, faster than a finger can deliberately press twice.
Keys are matched by the KeyboardEvent.code value, which names the physical position of a key rather than the character it types. That means the same test works on QWERTY, AZERTY, QWERTZ and Dvorak keyboards: the key in the Q position lights the Q position, whatever letter is printed on it.
How to Use Keyboard Tester
- Open the page — no download or permission needed
- Press every key; each one turns green once it registers
- Hold several keys together to check rollover
- Watch the chatter warning for any key that double-registers
- Show the navigation keys and numpad to test a full-size keyboard
Keys a Browser Cannot Always See
These are handled by the keyboard firmware or the operating system before the page gets an event. A gray key here is usually not a fault.
| Key | Why it may not register | How to check it instead |
|---|---|---|
| Fn | Handled inside the keyboard; never sent to the computer | Press Fn plus a media key and watch for the effect |
| Windows / Command | Often opens the Start menu or Spotlight first | Should still register on most systems; retry with the page focused |
| Print Screen | Often taken by the system for screenshots; browsers may see only the release | Check whether a screenshot is taken |
| Media and volume keys | Sent as consumer-control codes, not keyboard codes | Watch the system volume or media player |
| Caps Lock on macOS | Reported as one event per on/off change, not per press and release | Watch the Caps Lock light |
How to Read Your Result
A key does not light up
Press it several times, firmly and at different spots on the keycap. If it never registers on this page or in a text editor, the switch or membrane under it has failed; on mechanical boards, pulling the keycap and blowing out dust is the first thing to try. If it works in a text editor but not here, the operating system or another program is capturing it.
Chatter is flagged
One or two flags from very fast deliberate double taps are normal. Repeated flags when you press the key once and slowly mean the switch is bouncing — common on older mechanical switches. Cleaning can help; otherwise the switch needs replacing, or you can raise the debounce time in the keyboard’s software if it offers one.
Rollover stops at a low number
Many office and laptop keyboards register only 2 to 6 keys at once, and some combinations fewer, because of how the key matrix is wired. That is a design limit, not a fault. Gaming keyboards advertising N-key rollover should reach the number of keys you can physically hold.
Limitations & Accuracy Notes
- The test measures what reaches the browser; a key remapped by software shows up as the key it was mapped to.
- On-screen keyboards on phones and tablets do not send physical key positions, so they cannot be tested this way.
- Some USB keyboards cap reporting at six keys plus modifiers in their basic boot mode, which caps the rollover number you can see.
- Nothing you type is stored or sent anywhere; closing the page clears the results.
Frequently Asked Questions
How do I test my keyboard online?
What is keyboard rollover or ghosting?
What is key chatter?
Why don’t the Windows key or Fn key light up?
Does it work with non-US keyboards?
Can I test a laptop or phone keyboard?
References & Further Reading
- MDN — KeyboardEvent: code property — Physical key positions, independent of layout
- MDN — KeyboardEvent