Free · Client-side · No install

QMK Keyboard Tester

QMK Keyboard Tester is a free, browser-based tool to test QMK keyboards, layers and NKRO. It highlights pressed keys in real time, logs every event, and helps you validate keymaps and hardware without flashing firmware or installing drivers.

Works best on desktop & laptop browsers. On mobile, connect a USB or Bluetooth keyboard.

Event log

Time	Event	Key	Code	Layer

How to use the QMK Keyboard Tester

Start testing: Click Start Testing Keyboard or the Start Listening button. The online QMK tester will begin capturing keyboard events in your browser.
Switch layers: Use the Active layer dropdown to select or create layers (Base, Fn, Gaming). The keyboard legends are per-layer, ideal for visualizing QMK keymaps.
Press keys: Press any physical key. The matching virtual key highlights, and the event is logged with timestamp, event type, key, code and active layer.
Edit labels: Click a virtual key to set a legend that matches your QMK firmware (e.g., COPY, VOL+). This doesn’t flash firmware—only the test UI changes.
Check NKRO: Press multiple keys simultaneously. The stats panel shows current and maximum simultaneous keypress counts for simple NKRO testing.
Find missing keys: Click Show non-working keys to see keys that never registered during this session. This helps reveal wiring or matrix issues on custom builds.

QMK-specific tips

Layer validation: Align this tester’s layers with your QMK keymap file. Verify that every layer switch and momentary key behaves as expected.
NKRO limitations: The tester shows how many keys your OS and browser report. If you expect full NKRO but see rollover limits, check firmware settings and USB polling.
Keycodes vs positions: Browsers report event.code (physical position) and event.key (character). This qmk keyboard test uses code for consistent physical mapping.
No flashing required: Use the tool before flashing new firmware to confirm the physical matrix, and after flashing to confirm keycodes and layers.

About this online QMK keyboard test tool

This qmk keyboard tester is built for mechanical keyboard enthusiasts, QMK firmware users, and custom PCB designers who want a precise, browser-based way to debug keymaps and layers. Unlike generic mechanical keyboard testers, it is layer-aware: you can create Base, Fn, Gaming or Macro layers and attach visual legends to each key. Every keypress is logged with a timestamp and layer name so you can trace exactly how your board is behaving. For Korean users, a localized version of this online QMK tester is available via the language switch at the top of the page.

Why a browser-based online QMK tester?

Running in the browser makes this tool fast, portable and private. There is no installation, no driver configuration and no data upload. It’s an ideal companion while you edit your keymap.c file or tweak macros in VIA or Vial. Open the page, pick your layer, tap through every key, and watch the live NKRO test readout update as you press multiple keys together.

Privacy and limitations

The qmk keyboard tester runs entirely client-side, so key events never leave your device. Browser and OS security policies can limit detection of certain shortcuts (for example, Alt+Tab or system media keys), but for normal alphanumeric keys, modifiers and navigation keys, this tool is a reliable companion to QMK debugging. For low-level USB traces, combine this page with QMK console output or firmware logs.

Developer notes

Internally, the online QMK tester uses keydown and keyup handlers and maps event.code values to a standard ANSI-style layout. Layer labels are kept in memory for the current session and can be exported or imported as JSON. Everything is built with semantic HTML, modern CSS3 and minimal vanilla JavaScript so you can drop this file directly into /qmk-keyboard-tester/index.html on MouseTest.online without any build steps.

FAQ

How do I test my QMK keyboard online?: Open this qmk keyboard tester, click Start Listening and begin pressing keys. The virtual keyboard lights up in real time and the log records every press and release with keycodes and layers.
Can this QMK keyboard tester check NKRO?: Yes. The stats panel tracks how many keys are pressed at the same time and shows the maximum simultaneous press count. This gives a quick NKRO test for your mechanical keyboard, although true NKRO also depends on your controller and OS.
Do I need to flash firmware to use this tool?: No flashing is required. The online QMK tester simply reads what your operating system reports. It’s great for confirming that your current firmware and wiring behave as expected, but it cannot modify firmware.
Does this QMK tester work with all operating systems?: It works in modern browsers on Windows, macOS, Linux and ChromeOS. Some special keys or system shortcuts might not be visible due to OS-level handling, but standard QMK keycodes are usually detected correctly.
Is this QMK keyboard tester free?: Yes. The tool is completely free to use, runs purely in your browser, and doesn’t collect any keystroke data.
Can I save my keymap labels?: Use the Export mapping button to download a JSON file of your current layer labels. Later, you can paste that JSON into Import mapping to restore the same layout on another session.
What’s the difference between this and a generic keyboard tester?: This page is designed as an online QMK tester with layer support, key legend editing, NKRO stats and a detailed event log, so it’s more targeted at QMK and mechanical keyboard development than a simple keypress checker.