Conversions API (CAPI) – Meta & TikTok Server-Side Events
The Conversions API (CAPI) is the server-side interface from Meta and TikTok that sends conversion events directly from a website's server to the advertising platform, either alongside or instead of the browser-based pixel. This reduces data loss caused by ad blockers, ITP/Safari restrictions and cookie limits, because events no longer depend solely on the client browser. Meta and TikTok each run their own platform-specific APIs (Meta Conversions API, TikTok Events API) with separate event matching logic, deduplication and setup routes.
In practice
For small and medium-sized businesses, Meta's free "Meta-enabled Conversions API" feature has been relevant since April 2026: one click in Events Manager automatically mirrors all pixel events server-side including deduplication, with no developer or GTM setup at all – currently for web events only. Meta states an average 17.8% lower cost per result for ad accounts that connect CAPI in addition for web events (figure from Meta, April 2026; Meta publishes no methodology on sample or comparison group). TikTok's Events API, by contrast, still requires technical implementation (directly, through partners such as Stape or TAGGRS, or via a Shopify app), but it pays off particularly for shops connected to TikTok Shop. Important for agencies: both APIs need clean event matching (hashed email address, phone number, external ID) and combine well with a server-side tagging setup, but they are technically independent, platform-bound integrations and no substitute for it. Before rollout, test event match quality in the relevant Events or Ads Manager. Consent remains a precondition for server-side transmission too: the data originates from an action on the user's device, and passing hashed customer data on to Meta or TikTok needs its own legal basis. Both should be clarified legally before rollout.