How to use the keyboard tester
Click anywhere on the page so it has focus, then start pressing keys. Each key you press lights up on the on-screen keyboard while it is held and stays shaded once you release it, so you can work along every row and see at a glance which keys still need testing. Pick the layout that matches your physical keyboard first — Full (104/105 keys with a number pad), TKL (tenkeyless) or 60% — and switch between ANSI (the US-style layout with a wide, single-row Enter) and ISO (UK and most European layouts, with the tall L-shaped Enter and an extra key next to the left Shift).
The readout above the keyboard shows the last key's name, its physical code, the legacy keyCode, where on the board it sits (left or right for modifiers, numpad for the keypad) and how long you held it. Everything is logged in the history panel with a timestamp, and the whole session can be copied or downloaded as a report. Nothing leaves your browser.
On a phone or tablet, tap the Open on-screen keyboard field to bring up your device's virtual keyboard; keys you type will register in the log and in the readout, although a virtual keyboard cannot send every physical key code.
The same page works as a quick keyboard checker for a second-hand board or a laptop keyboard test after a spill: pick the 60% or TKL layout and run your finger along each row. If you need the exact event values for your own code, the JavaScript key code finder shows every property of a single press; once every key checks out, the typing test tells you how fast you type on it, and the mouse tester does the same job for buttons and the scroll wheel.
What the tester checks for
- Dead keys. A key that does nothing when pressed will never turn green. Try it several times and at different angles — a key that only registers with hard pressure usually has debris under the keycap or a worn dome.
- Stuck keys. If a key reports "down" for more than three seconds without a matching release, it is flagged as stuck. That is the classic symptom of a key whose switch is mechanically jammed or whose contact is bridged by a spill.
- Key chatter (double typing). Mechanical switches can wear so that one press sends two signals, which shows up as doubled letters when you type. The tester watches for a second press of the same key within 40 milliseconds of the first — far faster than a human can repeat — and lists any key that does it.
- Rollover and ghosting. Hold several keys at once. The held now counter shows how many the keyboard is reporting simultaneously and the max held figure is the most it managed this session. A board with 6-key rollover (6KRO) over USB will stop at six plus modifiers; an N-key rollover (NKRO) board keeps counting. If a key you are holding does not light up while others are down, that is ghosting.
- Auto-repeat. Hold a letter key down: after your operating system's repeat delay it starts sending repeat events, shown with a repeat badge and a live rate. Useful for checking a key isn't repeating on its own.
Reading the key codes
Browsers describe a key press three different ways, and the tester shows all of them because each is useful for something different.
| Field | What it tells you | Example |
|---|---|---|
key | The character or action the key produces with the current layout and modifiers. Changes with Shift, Caps Lock and language. | a, A, Enter |
code | The physical position of the key on the board, regardless of layout or language. The same for a French AZERTY and a US QWERTY board. | KeyA, ShiftLeft, Numpad7 |
keyCode | A legacy number that older software and games still use. Deprecated in web standards but still reported by every browser. | 65, 13 |
location | Distinguishes left and right modifiers and numpad keys that share a name. | 1 = left, 2 = right, 3 = numpad |
Click any entry in the history panel to copy its codes — handy when you are mapping keys in a game or writing a shortcut handler.
Keys a browser can't see
A web page only receives the keys the operating system and browser pass on, so a few keys will never register here even on a perfect keyboard: the Fn key on laptops (it is handled inside the keyboard itself), the Windows or Command key in some browsers, Print Screen on Windows (it fires only on release), and shortcuts the browser reserves such as Ctrl+W, Ctrl+T and Cmd+Q. Media keys (volume, play) and the power key are also usually intercepted by the system. The tester suppresses the browser's own reaction to most other keys — Tab, Space, Backspace, function keys — so that pressing them tests the key instead of scrolling the page or opening a menu.
Because of this, a key that stays grey is worth checking in a plain text editor before you decide it is broken. If it works there but not here, it is one of the reserved keys above rather than a hardware fault.
What to do about a bad key
A key that doesn't register or needs force: on a mechanical keyboard, pull the keycap and blow the switch out with compressed air, then press the switch stem directly — if it works bare, the cap was the problem. On a laptop or membrane board, a cotton bud with a little isopropyl alcohol around the key edges clears most sticky residue. Chatter: some keyboards let you set a debounce time in their software; otherwise the switch is wearing out and, on a hot-swap board, a two-minute swap. Stuck after a spill: unplug immediately, turn the board upside down, and leave it for at least 24 hours before testing again. Whole rows or blocks dead: that points at the controller or the ribbon cable rather than the keys, which on a laptop is usually a repair-shop job.
If you are testing a new keyboard for a return, download the report at the end of your session — it records every key pressed, every flag raised and your rollover result, with timestamps.
Frequently asked questions
Is this keyboard tester free and does it upload anything?
Yes and no respectively. The tester is free with no sign-up, and every key press is handled by JavaScript in your browser. Nothing you type is sent anywhere — you can confirm that in your browser's network panel.
Why does a key light up on the screen when I press a different one?
Your physical keyboard is a different layout from the one selected. Switch between ANSI and ISO and between Full, TKL and 60% until the on-screen board matches yours. Keys are matched by their physical position (the code), so a French or German board will still highlight the right key position even though the printed letter differs.
How do I test for key chatter?
Type normally for a minute or so, or press each key a few times at a normal speed. If a switch is chattering, the tester will see two presses of the same key within 40 ms — faster than any human — and add that key to the chatter list with a count. One or two flags on a key you were mashing can be noise; a key that keeps appearing is worn.
What is N-key rollover and how do I check it?
Rollover is how many keys the keyboard can report at the same time. Hold down as many keys as you can and watch the held now and max held counters. Most USB keyboards report up to six keys plus modifiers (6KRO); gaming and many mechanical boards report every key (NKRO). If a key you are holding stays dark while others are lit, the keyboard is ghosting that combination.
Does it work on a laptop keyboard and on a Mac?
Yes. Laptop keyboards are usually 60%/75% layouts without a numpad, so choose 60% or TKL. On a Mac the Command and Option keys are shown in their Mac positions when you pick the Mac labels, and the code values are identical to Windows.
Why won't Print Screen, Fn or the Windows key register?
The operating system or the keyboard itself handles those before the browser sees them. Fn never reaches software; Print Screen on Windows only sends a release event; the Windows/Command key is intercepted by some browsers. It doesn't mean the key is broken.