How It Works
Each test listens to the events your browser already receives from your device: key presses, mouse clicks, and pointer movement. It shows them as they arrive, measures the timing between them, and flags common faults such as a key that registers twice or a mouse button that double-clicks by itself.
Your browser only passes on what your operating system allows. Some keys, such as Fn, never reach a web page, and each test lists its limits.