It claims it's probably GDPR compliant, but it's pretty transparent about various possible caveats and such on the GDPR page[1].
[1]: https://www.goatcounter.com/gdpr
"There should always be an option to add GoatCounter to your site without requiring a GDPR consent notice."
"There should always be an option to add GoatCounter to your site without requiring a GDPR consent notice."