> We are fully GDPR compliant and use zero cookies.

From the GitHub repo [1]:

> At present, Fathom Analytics Lite is not PECR compliant due to the fact that it uses an anonymous cookie. Our PRO version is PECR compliant, and we'll be making changes to this codebase some time in the future to make it compliant.

The open source version seems to be lacking behind and might generally be treated without much love, given that their website doesn't even link to it (which is understandable from a business point of view, but doesn't inspire much confidence in its future maintenance).

[1]: https://github.com/usefathom/fathom/blob/69baac5c4a4d96880a2...