What Is Conversion API (CAPI) (CAPI)?
The Conversion API (CAPI) is Meta's server-side event stream: instead of the browser reporting events via the Pixel, your server (or a tag-management server, or your CRM) sends events directly to Meta. It recovers conversion signal lost to iOS 14.5+, cookie blocking, and ad-blockers — and it's now table-stakes for any account spending more than a few thousand a month.
How it fits with the Pixel
A user buys on your Shopify store. The Pixel fires 'Purchase' from the browser — but Safari drops the request. Meanwhile your server (via Shopify's CAPI integration or a CAPI Gateway) sends the same Purchase event with the user's hashed email and phone directly to Meta. Meta deduplicates using the shared event_id and keeps the one that landed. Conversion recovered.
Benchmarks
- Typical conversion recovery with CAPI live: +20% to +60% attributed conversions vs Pixel-only.
- Target EMQ (Event Match Quality): 7+/10.
- Deduplication rate: > 80% when Pixel + CAPI both fire with a shared event_id.
Why it matters
CAPI is the single biggest signal-recovery lever in the modern Meta stack. Without it, Advantage+ campaigns underperform, retargeting audiences shrink, and reported CPAs look artificially bad — which leads teams to cut spend on channels that are actually working.
Common mistakes
- 1.Not sending user data (hashed email, phone, external_id) — EMQ collapses to 3–5.
- 2.Missing event_id — Pixel + CAPI conversions get double-counted.
- 3.Only sending Purchase — send upper-funnel events too or Meta can't optimise.
Put Conversion API (CAPI) to work
Related services
FAQs about Conversion API (CAPI)
Do I still need the Pixel if I have CAPI?
Yes. Run both — the Pixel captures browser-specific signals (dwell time, add-to-carts) that pure server events miss. CAPI backs up the ones the browser drops.
How do I set up CAPI?
Three paths: (1) native integration if your platform supports it — Shopify, WooCommerce, Wix, HubSpot; (2) Meta CAPI Gateway on your subdomain; (3) server-side GTM. Native is easiest, GTM is most flexible.
What data should I send with each event?
Hashed email, hashed phone, external_id (your user ID), IP, user agent, fbc + fbp cookies, and event_id. That combination produces EMQ 8+ and near-perfect deduplication.
Related terms
Browser tag that reports events (view, add-to-cart, purchase) to Meta.
Meta's 0–10 score of how well events match to a Meta user.
Running Tag Manager on your own server to improve match + control.
How credit for a conversion is assigned across ad touchpoints.
Feeding CRM/sales data back to ad platforms to optimise on real outcomes.