Omikuji Tools Text & Dev

Keyboard Tester

Press any key and it lights up on the on-screen keyboard; keys you have tested stay colored. Check for dead keys, how many keys register at the same time, and keys that type twice (chatter) on one screen.

What this keyboard tester does

  • Keys light up on an on-screen keyboard as you press them and stay colored once tested, with a count of keys not yet tested
  • Shows the maximum number of keys registered at once (key rollover) and the keys currently held
  • Detects key chatter — the same key firing again a few milliseconds after release — with an adjustable 20–150 ms threshold
  • US and JIS layouts, with or without numpad. Shows key, code, keyCode and location (left vs right Shift, Ctrl and Alt)

When to use it

Buying a used laptop

Press every key on the spot to make sure none are dead or sticky before you pay.

A new keyboard arrives

Check for defects, confirm whether it is US or JIS, and make sure the numpad and right-hand Ctrl and Alt work.

After a spill

Once it has dried, look for keys that type by themselves, type twice, or do not respond.

Gaming keyboard rollover

Hold WASD with Shift and Space and see how many keys register without dropping any (n-key rollover).

Privacy

Key presses are only used to update this page. Nothing is sent anywhere and no record of what you type is kept. The browser only stores your settings: layout, numpad, chatter threshold and light/dark theme.

FAQ

A key does not light up. Is it broken?

First check that the status says “Testing”. Keys are only recorded while the keyboard area is selected, so if it says “Waiting”, click the keyboard drawing. A key that still does not light up may not be registering. However, Fn, combinations with the Windows key, and shortcuts the OS or browser handle first (Ctrl+W, Alt+Tab, etc.) never reach a web page even on a healthy keyboard. Try another app such as a text editor before deciding.

What is key chatter?

Chatter is a fault where the switch contacts bounce and one press is registered two or more times. This tool records a hit when the same key is pressed again less than the threshold (50 ms by default) after it was released. Human fingers almost never re-press the same key that fast, so a key that keeps showing up is likely chattering. Very fast tapping can also trigger it, so test at a normal pace.

How much key rollover do I need?

Typing needs 2–3 keys at once; games usually need around 6 (movement plus jump, crouch and so on). Budget keyboards may drop the third key in certain combinations to avoid ghosting, while gaming keyboards often offer n-key rollover so every key registers at once. Some USB modes limit rollover to 6 keys.

How do I tell a US keyboard from a JIS keyboard?

A JIS (Japanese) keyboard has a tall Enter key, Muhenkan / Henkan / Kana keys around the space bar, and extra ¥ and \ (ro) keys. A US keyboard has a wide Enter key and the \ key above Enter. Pick the layout whose shape matches your keyboard. If you press a JIS-only key while the US layout is shown, the page offers to switch.

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Layout
Numpad
Chatter threshold
50 ms
Not yet
0 keys
Tested 0 / 0
Max rollover
0 keys
now 0
Chatter
0 hits
50 ms

Testing — press any key Waiting — click here or Tab into it to start recording Esc × 2 to exit

While the test area is selected, Tab, Space, arrows and F-keys are recorded without moving the page. Press Esc twice to leave the test and use the buttons.

Last key

No key pressed yet
key
–
code
–
keyCode (legacy)
–
location
–

Keys held now

None

Keys not on the on-screen keyboard

None

Chatter log

    None yet

    Keys a browser cannot see

    Fn, PrintScreen on Windows (only its release reaches the page), shortcuts with the Windows key, and keys the OS or browser grabs first such as Ctrl+W, Ctrl+T, Ctrl+N, Alt+Tab and Alt+F4 never reach a web page. If one of these does not light up, the key is not necessarily broken — try it in another app such as a text editor.

    How to use

    1. Click the keyboard drawing (or Tab into it), then press keys. A key is blue while held, and stays green once it has been tested.
    2. Press every key once until “Not yet” reaches 0. Any key that never lights up is not registering.
    3. Hold your gaming combos (W, A, S, D + Shift + Space, etc.) together and read “Max rollover” to see how many keys register at once.
    4. A key that types twice from a single press gets a yellow outline and an entry in the chatter log. Adjust the threshold with − and +.