Keyboard Tester — Test Keys and Ghosting
A key-by-key keyboard tester with held keys and rollover count
Runs in your browser · nothing is uploaded
Click here, then press keys
- key
- –
- code
- –
- keyCode (legacy)
- –
- location
- –
- repeat
- –
- Modifiers
- –
Keys held right now
–
Most keys held at once
0
Keys tested
0 / 104
Recent events
No key presses yet.
While a Korean input method is active, key can read Process. Use code to identify the physical key.
Combinations the browser keeps (Ctrl+W, Ctrl+T, Ctrl+N, Alt+F4, Ctrl+Tab) and operating system keys (Win, Fn, some media keys) cannot be blocked or are never delivered to the page.
If several keys are held and some do not register, the keyboard hardware may have reached its simultaneous key limit (ghosting). This tool only shows input the browser actually received.
The keys you press are shown only on this screen and are not stored or sent to a server.
What it is
The Keyboard Tester lights up the matching key on an on-screen keyboard the moment you press it and shows the key, code, keyCode, location and repeat values the browser received. Use it to check a new keyboard for dead keys, to find the key that stopped responding on an old one, or to test the simultaneous key limit of a gaming keyboard. Every key you have pressed at least once stays green, so you can walk across the whole keyboard and spot the ones you missed.
How to use
- Click the dashed test area to give it focus. When the border darkens and the label says it is listening, you are ready.
- Press keys. A key is highlighted while held and stays green after you release it.
- Read the cards below for the last key’s key, code, keyCode, location (left, right or numpad), repeat flag and modifiers.
- Hold several keys together and watch the held-keys list and the most-keys-held counter. Test the combinations you really use.
- To stop, click outside the area or press Esc three times quickly. If you turn off the default-action blocking, Tab and Space work as usual again.
- Clear wipes the green marks and the maximum count.
What the values mean
- code: the physical position of a key, such as KeyA for the A key. It stays the same when the layout or language changes, which is why the on-screen keyboard is driven by it.
- key: the character or key name produced, such as a, A or Enter. It changes with Shift and with the input language, and reads Process while an input method editor is composing.
- keyCode: an old numeric value. It is deprecated but shown so you can compare with legacy code.
- location: tells duplicate keys apart: 0 standard, 1 left, 2 right, 3 numpad.
- Held keys: a key counts as held after the browser got keydown and before it gets keyup. If the test area loses focus, everything is treated as released.
- What cannot be blocked: Ctrl+W, Ctrl+T, Ctrl+N, Alt+F4, Ctrl+Tab, the Windows key and Fn are handled by the browser or operating system and cannot be stopped or never arrive.
- Korean layout: you can show the standard 2-set Hangul letters on the keys, and the 106-key layout includes the Hangul (Lang1) and Hanja (Lang2) keys. With the common Windows Korean keyboard setting, Hangul arrives as right Alt (key value HangulMode) and Hanja as right Ctrl (HanjaMode); such a press lights both the Hangul/Hanja key and the Alt/Ctrl in that position.
Examples
| Key pressed | key | code | location |
|---|---|---|---|
| Left Shift | Shift | ShiftLeft | 1 (left) |
| Right Shift | Shift | ShiftRight | 2 (right) |
| Numpad 5 | 5 | Numpad5 | 3 (numpad) |
| Top row 5 | 5 | Digit5 | 0 (standard) |
| Space bar | (space) | Space | 0 (standard) |
Numpad 5 and top-row 5 report the same key value but different code and location, so you can tell which one responds. On a Mac, keyup may not be delivered for other keys while Command is held, so a key can look stuck. Press Clear if that happens.
FAQ
Some keys do not light up. Are they broken?
Click the test area first so it has focus. Fn, many media keys and keys the operating system handles first, such as the Windows key or screenshot keys, often never reach the browser. If an ordinary letter key stays dark, it may be dirty or faulty, so try it in another program too.
What is ghosting and how do I check it?
Ghosting is a hardware limit where pressing several keys at once makes some presses disappear or makes a key appear pressed when it was not. Hold the combination you actually use, for example the movement and jump keys in a game, and compare the held-keys list and the maximum count with the number of keys you pressed. If the count is lower, the keyboard or its connection cannot report that combination.
Why can the tester not block Ctrl+W or Alt+F4?
Combinations that close tabs or windows are taken by the browser or operating system before the page can react, so no web page can stop them. The same goes for Ctrl+Tab and Windows key shortcuts. This tool does stop the scrolling and focus changes caused by keys like Tab, F5, arrows and Space, and it deliberately leaves developer tool shortcuts such as F12 alone.
Why does key show Process when I type Korean?
When an input method editor handles the key first, the browser reports key as Process. The physical key is still available as code, such as KeyA, so the on-screen keyboard keeps working.
Are my key presses sent anywhere?
No. Presses are shown only on this screen and are never stored or transmitted. The tool only reads keys while the test area on this page has focus.
