How to use the Keyboard Tester
- Press every key on your keyboard, one by one. Each one turns green once it's detected.
- A key that doesn't light up may be broken, or it may be a key the browser can't see (see the notes below).
- To test rollover, hold down several keys together and watch held now and most at once.
- Click Reset to start again.
Keys a browser can't test
Some keys are handled by your operating system before the browser sees them, so they may not light up even when they work:
- Fn, and media keys like volume and brightness on most laptops.
- Windows / Command combinations, and Print Screen on some systems.
- Shortcuts like Ctrl+W, Ctrl+T or Alt+F4, which the browser or system always handles. Don't press these!
What is key rollover and ghosting?
Rollover is how many keys a keyboard can register at the same time. Cheap keyboards often manage only 2 or 3 keys in some combinations. Gaming keyboards advertise "N-key rollover" (NKRO), meaning every key. When a keyboard can't detect a combination, keys get missed, or a key you didn't press appears: that's ghosting. Hold several keys and check most at once.
Fixing a key that doesn't work
- Try another USB port, or new batteries for wireless keyboards.
- Blow out crumbs with compressed air, or gently lift the keycap and clean underneath.
- Test the keyboard on another computer. If the key works there, check your keyboard layout and drivers.
Frequently asked questions
Why doesn't my Fn key light up?
Fn is handled inside the keyboard itself and never reaches the computer, so no website can detect it.
What's the difference between event.key and event.code?
<code>key</code> is the character produced, which depends on your language layout. <code>code</code> is the physical key position, which stays the same whatever the layout.
Will pressing keys here change anything on my computer?
Normal keys don't. With <b>Capture keys</b> on, keys like Tab, F5 and the arrows are blocked so they don't scroll or reload the page.
Does it work with non-US keyboards?
Yes. Keys are matched by their physical position, so the picture shows US labels, but every key on your keyboard is detected.