About KeyTest

KeyTest was built to answer a simple question quickly: does every key on this keyboard actually work? Instead of opening a text editor and mashing keys, you get a clear on-screen keyboard that lights up exactly which physical key you pressed, plus a mouse diagram for clicks and scrolling. It's useful for checking new or second-hand hardware, for streamers who want to show their inputs, for typing practice, and for developers who need to see the precise key code a button emits.

What makes it different

• Position-accurate. Keys are matched by their physical code, so the highlight is correct regardless of your operating system's input language.
• Multiple layouts. Switch between US English, Spanish (Spain), Spanish (Latin America), and Apple keyboards.
• Goes beyond the basics. A dedicated panel covers the numeric keypad and rarely-seen USB HID keys, including F13–F24 and media controls.
• Private by design. Everything runs locally in your browser. Keystrokes are never stored or sent anywhere.

How it works

KeyTest is a small, dependency-free web app — just HTML, CSS, and JavaScript. It listens for standard browser keyboard and mouse events and maps each one to an element on screen. There is no backend and no analytics on your input; the visualization happens entirely on your device. The site is hosted as static files on a content delivery network for speed and reliability.

Who made it

KeyTest is a maker project by Lalo Solo (Eduardo Cortés Trujillo), a computer-science engineer who builds electronics, designs for 3D printing, and shares projects online. You can find more of his work at lalosolo.com and on YouTube.

Get in touch

Found a bug, or have a key that isn't mapped correctly? Suggestions are welcome — see the contact page.