Free keyboard tester

1. Click “Start testing.” This arms the tool so it can listen for key presses and, for a handful of keys like Space and the arrow keys, stop the page from scrolling while you test.
2. Press every key on your keyboard, row by row. Start at the top-left with Esc and the function keys, work across the number row, then the letter rows, then the bottom row and arrow cluster.
3. Watch the on-screen layout. A key currently held down fills solid; once released, it turns green to mark it as tested. Anything still grey hasn't been pressed yet.
4. Check the counters. “Keys tested” tracks your progress toward covering the whole board, “total keypresses” counts every press, and “max keys held at once” is your anti-ghosting number — see below.
5. Use the typing box to sanity-check output. Click into the small text area and type a sentence. If what appears doesn't match what you pressed, you've likely found a key that's mapped or typing incorrectly.
6. Click Reset to clear all progress and re-test from scratch — handy when testing a second keyboard or checking a repair.

Because everything runs client-side using the browser's built-in keyboard events, there's no software to install, no permissions to grant beyond a normal webpage, and it works on Windows, macOS, Linux, and Chromebooks alike.

A dead key is one that produces no key event at all — you press it and nothing happens, anywhere. A stuck key is different and more disruptive: the switch fails to register a release, so the operating system thinks it's still being held down long after your finger has lifted, which can spam a character repeatedly or block other input.

• To find a dead key: work through every key on the on-screen layout in order. Any key that stays grey no matter how firmly or how many times you press it is either dead or not reaching the browser (see the Fn note below).
• To find a stuck key: press and release each key deliberately, one at a time, and watch the “last key” readout and the on-screen cap. If a key fills in as “pressed” and never returns to its tested/green state after you've clearly released it, that's a stuck key — the keyup event never fired.
• Test under real conditions. Dust, spilled liquid residue, and worn switches often only fail intermittently. Press each suspect key firmly 10–20 times and from slightly different angles before ruling it out.
• Compare with the typing box. If a key shows as tested here but produces the wrong character (or nothing) in the typing box, the switch itself is fine — the problem is in the keyboard layout or driver mapping, not the hardware.

A stuck key is more urgent to fix than a dead one: in games it can cause runaway movement, and in normal typing it silently repeats a character until you notice. If Reset doesn't clear a “pressed” state, reload the page — a stuck key on the hardware itself will show the same symptom again immediately.

Key rollover is how many keys a keyboard can register as pressed at the same time. Ghosting is what happens when it runs out of rollover: pressing a third or fourth key combination causes a “phantom” key press that was never touched, or causes one of the real presses to simply not register.

Ghosting is a wiring limitation, not a software bug. Cheaper membrane keyboards scan keys in a grid of rows and columns; press the wrong combination of three keys in the same row/column intersections and the controller can't tell which keys are actually down. Manufacturers solve this with:

• 2-key rollover (2KRO): the baseline — any two keys work together reliably, but a third can misbehave. Fine for typing, limiting for gaming.
• 6-key rollover (6KRO): common on USB keyboards; up to six non-conflicting keys register simultaneously, which covers almost all real typing and most games.
• N-key rollover (NKRO): every key has its own dedicated line (or is diode-protected), so any number of keys can be held at once with zero ghosting — the standard for competitive gaming keyboards.

Use the “max keys held at once” counter on this tool to check your rollover in practice: hold down a common combo for your use case (for example W+A+Space, or Ctrl+Shift+Esc) and watch the counter and the on-screen layout. If a key you're physically holding drops off the “pressed” highlight while others are still down, or a key you never touched lights up, that's ghosting in action. Try several different key combinations, since ghosting is specific to which keys share a row or column on the internal matrix — one three-key combo may ghost while another works perfectly.

The practical difference for testing: on a membrane keyboard, a failure often clusters around keys that share the same row/column on the underlying matrix, so if one key is flaky, test its neighbors too. On a mechanical keyboard, failures are usually isolated to a single switch — if it's a hot-swappable board, testing here first tells you exactly which switch to pull and replace instead of guessing.

Rollover also differs by design intent rather than just switch type: many budget mechanical keyboards still ship with 6KRO over USB, while some membrane keyboards marketed for gaming add anti-ghosting circuitry on a specific cluster of keys (usually WASD plus modifiers). Don't assume — use the max-simultaneous counter above to check your specific board rather than relying on the switch type alone.

If a key registers here (turns green, shows a code and keyCode) but the typing box shows the wrong character, the hardware is working and the problem is almost always software:

• Wrong keyboard layout selected. The most common cause by far. If pressing the key next to Enter types ; when you expect é (or vice versa), your OS is set to the wrong regional layout — check Settings → Language/Keyboard and match it to your physical keyboard's printed layout (QWERTY, AZERTY, QWERTZ, etc.).
• A stuck modifier. If every letter comes out capitalized or symbol row keys type numbers, Caps Lock, Shift, or Num Lock may be toggled on. Check the on-screen lock indicators on your keyboard or OS, or simply tap the modifier key again.
• Remapped keys. Software like PowerToys Keyboard Manager (Windows), Karabiner-Elements (Mac), or manufacturer keyboard software can remap individual keys. If the code shown by this tool is correct (e.g. KeyA) but the key value is wrong, remapping software is intercepting the signal before the browser sees the raw key.
• A physically damaged or swapped keycap. If someone popped keycaps off to clean the board and put one back in the wrong spot, the printed letter won't match what the switch underneath actually sends — the on-screen layout here reflects the real electrical signal, not the printed cap.
• Browser extensions intercepting keys. Rarely, an extension with global keyboard shortcuts can swallow or rewrite events. Test in a private/incognito window with extensions disabled to rule this out.

Use the key / code / keyCode readout on this tool as your diagnostic anchor: code identifies the physical switch regardless of layout or language, while key shows what character your current OS layout actually produces. When those two disagree with what you expect, you now know whether to fix a setting or replace a switch.

Many laptops route Fn-combined shortcuts — screen brightness, volume, media playback, airplane mode — through embedded controller firmware rather than sending a normal key event to the operating system. That means they can be completely invisible to a browser-based tester like this one even though the hardware is working perfectly. If a function key looks “dead” here but changes your brightness or volume when pressed, that's expected behavior, not a fault. To test those specific functions, use your laptop manufacturer's diagnostic utility, which can read hardware-level signals a webpage cannot.

• Buying secondhand. Confirm every key on a used mechanical or laptop keyboard actually registers before you agree to a purchase — a dead key is easy to miss in a quick glance but obvious once you've pressed every key on this layout.
• Before a remote interview or exam. A stuck or ghosting key mid-interview or mid-timed-test is a bad time to discover a hardware problem. Run a 60-second check beforehand.
• Diagnosing gaming issues. If character movement feels inconsistent or a combo input drops randomly, check rollover with the max-simultaneous counter before blaming the game.
• After a spill or drop. Liquid and dust are the top causes of intermittent stuck and dead keys. A full sweep across every key catches partial failures a normal typing session would miss.
• Verifying a repair. After replacing a switch, cleaning a membrane, or reseating a keyboard ribbon cable, retest the whole board to confirm the fix worked and nothing else was disturbed.