I am currently investigating server side tracking, in particular, its ability to overcome Safari's ITP for cross domain tracking. Could HTTP response headers be used to set a unique visitor ID on domain one and then retrieve it on domain two? My research found a potential solution that can be used in Google Analytics using FPID and FPLC cookies but I am unsure whether this solution will circumvent Safari's ITP as JavaScript is used to access the FPLC cookie value and the value is also upended to the URL of the 2nd domain as a query string parameter. Safari's criteria when applying the 24 hour expiration of a cookie is whether or not a URL has query string parameters so this made me question whether this method would work.
I read this article on server side cross domain tracking by Simo Ahava which made me raise this question:
https://www.simoahava.com/gtm-tips/cross-domain-tracking-server-side-fpid-cookie/
Any guidance/advice on this topic would be much appreciated.
Many thanks
Liam
I haven't tried anything yet, I am wanting to understand whether the HTTP response header server side tracking method would work to send unique visitor IDs across domains to allow for cross-domain tracking on my website and whether this method could circumvent Safari's ITP.