Measures how this browser renders text, canvas and CSS units, so a test environment can reproduce it.
Together this is enough to recognise your specific machine. It does not read your files, browsing history, cookies, passwords, or anything you type. The result is sent back to the person who shared this link with you. Only run it if you agreed to share it with them.
Set browser zoom to 100% (Ctrl+0). Zoom changes the display
scaling and makes every measurement unusable. Keep this tab in the foreground — it
runs on its own and takes about a second.