Glossary

Server-to-server (S2S) tracking

Server-to-server (S2S) tracking is a method of conversion tracking where the advertiser's server notifies the tracker's server directly — via a postback URL carrying a click ID — instead of loading a pixel in the visitor's browser. No cookies or client-side code are involved in confirming the conversion.

S2S vs pixel tracking

A pixel fires in the browser, so it dies with ad blockers, cookie consent walls, Safari's tracking prevention, or a user closing the tab too early. An S2S postback fires from infrastructure the advertiser controls, after the conversion is validated — making it the default choice wherever payouts depend on accurate numbers.

The trade-off is integration effort: the advertiser must store the click ID through the funnel and fire the postback on conversion, rather than pasting a snippet into a thank-you page.

In practice

Virtually all CPA networks and affiliate trackers speak S2S natively. Integrating a new offer usually means one thing: mapping where the click ID goes in (a URL parameter) and where it comes back (the postback template with a {click_id} macro).

Related terms