How to test your keyboard
- Press any key — or click the drawn keyboard first. The test area gets a blue frame and the box above it turns green: from now on every key press is captured.
- Press each key once. A key lights up blue while you hold it down and stays green after it has worked. A key that stays white when you press it did not reach the computer.
- Watch the details below the keyboard: event.key (the character or function the key produces), event.code (the physical key), its location and the legacy keyCode.
- Hold several keys together to see Keys held now and Most keys at once — the rollover check described below.
- Press Reset test to start over. To leave the test area with the keyboard alone, press Esc and then Tab.
Choose the layout that matches your keyboard: ANSI (US style, 104 keys, a wide Enter key and a long left Shift) or ISO (common in Europe, 105 keys, a tall Enter key and an extra key between left Shift and Z). The test switches to ISO by itself when you press that extra key. In Chrome and Edge, the letters on the drawn keys follow the layout set in your system — AZERTY, QWERTZ and others.
How it works
Every key press sends the browser a keyboard event with two different names for it. event.code names the physical key by its position on a US keyboard — KeyQ is the key next to Tab whether it types Q, A (French AZERTY) or something else. event.key is what the key means right now: "q", "Q" with Shift, "Enter" or "ArrowLeft". The tester lights keys by their code, so it checks the hardware, not your language settings. Location tells apart keys that exist twice: left or right Shift, Ctrl and Alt, and the numeric keypad's Enter, digits and operators. keyCode is an older number that websites used before these names existed; it is shown because many developers still look it up.
Rollover and ghosting
Key rollover is how many keys a keyboard reports at the same time. Gamers and fast typists need several: a chord such as Shift + W + A + Space is four keys at once. Many office keyboards connected over USB use the basic report format, which has room for six ordinary keys plus the modifier keys (Ctrl, Shift, Alt, Windows/Command); keyboards sold as N-key rollover report every key you press.
Ghosting happens on keyboards whose key grid has no diodes: certain combinations of three keys make a fourth, unpressed key appear. To prevent this, many keyboards block (“jam”) the extra key instead, so a key you are holding simply doesn’t register.
Example: a rollover check
Rest your fingers on A S D F and J K L ; and press all eight one after another without letting go. On a keyboard with full rollover, Keys held now climbs to 8 and all eight keys are blue. If it stops at 6, the keyboard reports six keys at a time. If it stops at 3 or 4, or a key you are holding stays white, that combination is blocked by the keyboard’s matrix. Try the keys your games use, such as W, A, S, D with Shift and Space.
Tips and limits
- Fn key: on most laptops it is handled inside the keyboard and never reaches the browser, so it can’t light up. Test it through what it does: Fn + a function key should produce that key’s other function.
- System shortcuts belong to the operating system and can’t be captured by a web page: the Windows key opens the Start menu, Alt + Tab switches windows, and Ctrl + Alt + Delete is reserved. Avoid Ctrl + W and Alt + F4 on Windows, and ⌘W or ⌘Q on a Mac — they close the tab or the browser.
- Print Screen: some systems take the key for a screenshot and pass only its release to the browser. The tester counts the release, so the key still turns green.
- Mac: macOS doesn’t report releasing other keys while ⌘ is held; the tester clears the held keys when you let go of ⌘.
- Laptops often have no numeric keypad, Insert or Scroll Lock, so those keys stay white. Number keys on the keypad send digits only while Num Lock is on.
- A key repeats or types twice? Dust or a worn switch can make a key bounce. Count your presses in the typing test, or check a mouse button the same way with the CPS test.
- Phones and tablets use touch keyboards, which don’t send physical key codes. Connect a Bluetooth or USB keyboard to test it here.
When the keys work, measure how fast you type with the typing test, or test your reflexes with the reaction time test.
Frequently asked questions
How do I know if a key on my keyboard is broken?
Press it while the test area is active. A working key lights up blue while held and then stays green. If it stays white, the computer never received it: try it again firmly, check for dirt under the key cap, and test the keyboard on another USB port or computer to rule out the cable or the port.
Why does a key light up but type the wrong character?
The hardware works and the keyboard layout in your system is different from the labels on your keys — for example a US layout selected for a UK or German keyboard. Change the input language or layout in your system settings. The event.key value shows what the key types with the current layout.
What is the difference between key rollover and ghosting?
Rollover is how many keys a keyboard can report at the same time; ghosting is a phantom key that appears when several keys are held on a keyboard without diodes in its key grid. Most keyboards avoid ghosting by blocking the extra key, which shows up here as a held key that stays white.
Can I test a laptop keyboard?
Yes. Laptop keyboards usually lack a numeric keypad and some navigation keys, so those keys stay white on the full-size drawing. The Fn key is handled inside most laptop keyboards and is not visible to a browser.
Does the keyboard tester record what I type?
No. The key presses are shown on this page only. Nothing is stored or sent to a server, and nothing remains after you close the page.
Last updated: October 15, 2026