Who's watching when you visit a site?
Most websites load code from other companies: analytics, advertising networks, social media buttons, session recorders and tag managers. Each one learns that you visited the page, and many follow you from site to site. The scanner lists them before you visit.
How the grade works
The grade counts the tracking companies loaded straight away: A none, B one or two, C up to five, D up to ten, F more. Fonts, video players, payment and support tools are listed separately and don't lower the grade, although they also see your IP address. Scripts that a cookie banner holds back until you accept are shown under "Waiting for consent".
A page over the 3 MiB reading limit gets partial findings and no grade. If redirects exceed the fetch limit, the scanner stops without grading a page it has not fetched.
Questions
Why doesn't it find every tracker?
We read the page's HTML once and don't run its scripts. Tag managers and ad networks often load more trackers after the page opens, so the real number is usually higher.
Does the site see me when I scan it?
No. Our server fetches the page, so the site sees our server, not you.
Do you keep the sites I scan?
No. Addresses aren't logged. Results are cached for 30 minutes under a scrambled key, then removed.