# Keyboard Tester: Check Every Key Online

> Free online keyboard tester: press keys to light them up on an ANSI or ISO layout, with key codes, an event log and Windows or Mac labels.

Canonical page: https://controllertests.com/keyboard-test/

Press every key on your keyboard — each one lights up the moment your browser receives it, so dead, stuck or swapped keys stand out instantly.

**Interactive tool:** this page hosts a free test that runs locally in the visitor's web browser (no install, no upload). To use it, open https://controllertests.com/keyboard-test/ in a browser on the device that has the hardware attached.

## Reading the result

Each key turns **green** the first time the browser receives it, so a fully green board means every key is electrically working and reaches your operating system. A key that is **lit solid** is being held right now — if it stays lit after you let go, the switch is sticking or its release signal was lost.

- **A key never lights up:** the switch, its contact or the keyboard matrix may be faulty — or the key is handled by the keyboard itself (like `Fn`) or swallowed by the operating system. Check the limits below before assuming a hardware fault.
- **A different key lights up:** the board shows physical positions, so this points to a remap in keyboard software, the OS or a utility such as PowerToys or Karabiner — not your language layout.
- **One press lights the key twice in the log:** that is chattering. Run the [chattering test](https://controllertests.com/keyboard-test/chattering/) to measure it.
- **Keys drop out when you hold several:** that is a rollover limit. The [rollover and ghosting test](https://controllertests.com/keyboard-test/n-key-rollover/) shows how many keys your keyboard reports at once.

## How to use the keyboard tester

1. Pick your physical layout: **ANSI** (US-style, wide Enter) or **ISO** (tall Enter and an extra key next to left Shift), and Windows or Mac labels.
2. Press every key once, row by row. Watch the counter climb toward the total.
3. Turn on *Highlight keys not pressed yet* to spot the ones you missed — or the ones that never respond.
4. Hold a key to check that it stays lit and releases cleanly. Use the event log to compare press and release times.
5. Use *Copy result* to paste a summary into a support ticket or warranty claim.

## What is measured and the limits

The tester listens to standard keyboard events. For every press it reads `KeyboardEvent.code`, which identifies the *physical* key position regardless of language or layout, plus `key` (the character it produces), the legacy `keyCode`, the `location` (left, right or numpad) and whether the event is an auto-repeat. Times come from the event's high-resolution timestamp, in milliseconds since the page loaded.

Some keys never reach a web page, so a key that stays dark is not always broken:

- `Fn` is handled inside the keyboard and sends nothing of its own. It is drawn dashed on the Mac layout for that reason.
- Operating-system shortcuts such as `Ctrl` + `Alt` + `Del`, `Win` + `L`, `Alt` + `Tab` or `⌘` + `Tab` are captured before the browser sees them. The `Win` key alone usually works.
- Browser shortcuts with `Ctrl` or `⌘` keep working on purpose, so you can still close or reload the tab.
- On Windows, `Print Screen` often sends only a key release. The tester counts it anyway and marks it “up only” in the log.
- On a Mac, `Caps Lock` reports its on/off state, so it may light only on every second press. Media keys can be taken over by the system's media controls.

## Browser and device support

| Platform | Physical key codes | Notes |
| --- | --- | --- |
| Chrome, Edge, Opera (Windows, macOS, Linux, ChromeOS) | Yes | Full support. Print Screen may be release-only on Windows. |
| Firefox (desktop) | Yes | Full support. Holding `Alt` no longer opens the menu bar here. |
| Safari (macOS) | Yes | Caps Lock reports on/off state; system shortcuts are hidden. |
| Android or iPadOS with a hardware keyboard | Mostly | Most keys work; some system keys are reserved by the OS. |
| On-screen (touch) keyboards | No | They type characters but have no physical key positions to test. |

## If a key doesn't work

1. Try a different USB port or cable, or re-pair a wireless keyboard, then test again.
2. On Windows, check that *Filter Keys* is off (Settings → Accessibility → Keyboard); it can ignore brief presses. On a Mac, check *Slow Keys*.
3. Remove the keycap if your keyboard allows it and clear debris with compressed air. On hot-swap mechanical keyboards, re-seat or swap the switch.
4. If the same key fails on another computer too, it is a hardware fault — the copied result is useful evidence for a repair or warranty claim.

## More keyboard tests

[
### Keyboard chattering test

Find keys that type twice: release-to-press gaps per key and a heatmap.](https://controllertests.com/keyboard-test/chattering/)[
### Rollover & ghosting test

How many keys register at once? Check NKRO, 6KRO and ghosting.](https://controllertests.com/keyboard-test/n-key-rollover/)

## Frequently asked questions

### How do I test my keyboard online?

Open this page and press each key. Every key that works turns green on the diagram, and the counter shows how many of the layout's keys have registered. No download or sign-up is needed.

### Why doesn't my Fn key light up?

The Fn key is processed inside the keyboard to change what other keys send. It never produces a key event of its own, so no website or app can detect it. Test it by pressing an Fn combination (such as Fn + F-key) and watching which key lights up.

### What is the difference between ANSI and ISO keyboards?

ANSI keyboards (common in the US) have a wide, single-row Enter key and a long left Shift. ISO keyboards (common in Europe) have a tall, L-shaped Enter and an extra key between left Shift and Z. Pick the one that matches your keyboard so every key has a place on the diagram.

### Does the keyboard tester work on a laptop or Mac?

Yes. Built-in laptop keyboards and Mac keyboards work in any modern browser. Switch to Mac labels to see ⌘ Command, ⌥ Option and ⌃ Control in their usual positions.

### Is anything I type recorded?

No. Key events are processed only in your browser to light the diagram. Nothing is sent anywhere, and the log disappears when you reset or close the page.

## Related tests

- [Keyboard chattering test](https://controllertests.com/keyboard-test/chattering/)
- [Rollover & ghosting test](https://controllertests.com/keyboard-test/n-key-rollover/)
- [Mouse tester](https://controllertests.com/mouse-test/)
- [Spacebar counter](https://controllertests.com/cps-test/spacebar-counter/)
- [Reaction time test](https://controllertests.com/reaction-time-test/)

_Last updated: 2026-10-01_