Conversions API

A Conversions API is a channel that tells an ad company whether someone actually bought something or signed up after seeing an ad. It's a bit like confirming a signature after a package is delivered. A small tracking marker placed at the moment of an ad click (often called a pixel) can lose the trail if a user blocks ads or switches browsers, but a Conversions API fills that gap because the advertiser's own server sends outcomes like completed payments directly to the ad platform's server.

The ad platform uses this information to figure out which ads actually led to sales, then adjusts bidding and targeting to show that ad more effectively to similar users. So the Conversions API isn't a feature users see—it's more of a backend signal that reports whether an ad actually worked.

In coverage of ChatGPT's ad business, the article notes that "the pixel and the Conversions API became the foundation for measurement and optimization." A common misunderstanding: the Conversions API doesn't create or display ads—it's a backend mechanism where the advertiser's server reports real outcomes after someone saw an ad to the ad platform.