Campaign Attribution

UTM parameters are tags appended to campaign URLs that identify the source, medium, and campaign name of a visit. utm_source identifies the platform (google, newsletter, twitter), utm_medium identifies the channel type (cpc, email, social), utm_campaign identifies the specific campaign. They were originally developed for Google Analytics but are now a standard attribution mechanism used across analytics platforms.

Safari ITP and Brave remove certain URL parameters they classify as tracking parameters. UTM parameters are among those targeted. The removal happens before the page's JavaScript executes, so client-side analytics tools that read UTM values from the URL cannot recover them. Server-side attribution reads the URL at the HTTP request level, before this removal, though the browser may modify the URL in its request before it even reaches the server in some contexts.

The Campaign Link Builder is a free browser-based tool at /tools/campaign-link-builder/ that generates campaign URLs with both standard UTM parameters and the c_ alias equivalents. It also shows which parameters Safari and Brave would strip from a given URL, so you can see the difference between a standard UTM link and a privacy-resilient c_ alias link.

Referral attribution identifies where traffic came from based on the referrer header (which external site sent the visitor). Campaign attribution identifies which specific campaign sent the visitor based on UTM parameters you added to your campaign links. A visitor from an email newsletter without UTM parameters appears as Email traffic. A visitor from the same newsletter with UTM parameters appears as Campaign traffic with your campaign name as the source.