Is Facebook CAPI necessary for tracking users after third-party cookies are phased out?

I guess I'm misunderstanding something. Any help is much appreciated. TIA!

So, CAPI was released because Facebook needed third-party cookies to track users, and also Google Chrome (the largest market share for any search engine) blocking third-party cookies by Q2-2025. This would make Facebook pixel useless, according to several marketing blogs.

But when I check my browser’s dev tools, I see that the Facebook pixel creates a _fbp cookie in a first-party context, plus an _fbc cookie if the visitor arrives via a Facebook ad. These cookies are unique to the user and the site. The pixel then sends the cookie values as query parameters in the GET requests to Facebook servers for each event.

So, if the Facebook pixel is already using first-party cookies and adding their values to the URL, I’m confused about why we need the Conversions API. It's supposed to fix the issue of third-party cookie blocking, but since we're dealing with first-party cookies and sending their values in the URL, I don’t get what problem CAPI is solving.

Could someone clarify this for me? Any assistance would be greatly appreciated! Thank you!

The logic makes sense, but the confusion seems to come from the terminology. Facebook often compares third-party cookies with first-party data. First-party data includes info that users voluntarily provide, like emails, phone numbers, and persistent IDs used by apps or stores.

When the Facebook pixel tracks an event using JavaScript, it can access the _fbp cookie, which might be tied to a paid ad click or something else. For example, on a purchase thank-you page, there might not be any personally identifiable info available.

On the other hand, server-side data includes more detailed info, like the original click ID, name, and email if the user has signed up before. This makes server-side integration better for attributing conversions compared to just pixel tracking.

The problem with first-party cookies is that, ideally, cross-domain third-party cookies would be used, giving the tracking pixel access to facebook.com cookies on any site. However third-party cookies have been blocked in Safari for years and will be phased out in Chrome by 2024.

So, the industry has moved to first-party cookies combined with server-side integration. First-party cookies might be enough for immediate purchases, but they're limited for broader tracking. The Conversions API, with access to original click IDs, cookies, and personal data, gives much better data accuracy in Ads Manager than pixel tracking alone.