Recently I was following up with a prospect about a Server-side Google Tag Manager (SS-GTM) proposal. They replied noting that their Facebook rep told them Facebook has a Conversions API Gateway (CAGI) solution that is much easier, and less costly, to stand up than SS-GTM. Let’s take a look at how they compare.

Facebook’s Conversions API Gateway solution seems to be “SS-GTM-lite”, only supporting delivery of Facebook signals. Facebook proposes (validity TBD) this solution is:

Basically, this solution is engaged from the Facebook Events Manager settings, and causes the Facebook pixel to also send signals to a Conversions API Gateway instance hosted on Amazon Web Services (separate setup required), akin to how SS-GTM needs to be hosted in the cloud (multiple hosting options with SS-GTM). Data is sent via a subdomain of the domain hosting the website (first party context), so that’s like SS-GTM. Facebook’s Conversions API Gateway passes the signal to Facebook via their Conversions API as an event. With this solution, the Facebook pixel continues to send the event directly to Facebook from the browser as usual, with automatic consideration for deduplication.

How does this compare to Server-side Google Tag Manager?

Here’s our top 5 points of comparison absent a deeper dive:

  1. There is a hosting cost just like there is with SS-GTM (you pay Amazon Web Services for hosting with Facebook’s solution).
  2. Their solution is Facebook specific, so no support for Google Analytics, both UA & GA4Google Ads conversionsGoogle Ads remarketing and Google Floodlight tags (nor the other platforms that are forthcoming) as with SS-GTM.
  3. You have zero control over their solution, whereas with SS-GTM you have total control (including setting HTTP cookies).
  4. There is no path for integration with cookie consent tools like OneTrust.
  5. There is no way to host the Facebook JavaScript library with first party context (it will still be very susceptible to not being initialized due to ad blockers / stringent browser security settings).
Facebook Conversions API Gateway or Server-side Google Tag Manager?