Facebook Conversions API (CAPI)
Meta's server-to-server interface that lets advertisers send web, app, and offline conversion events directly from their server to Meta, bypassing the browser and improving data reliability for ad optimization.
What is the Facebook Conversions API?
The Facebook Conversions API (CAPI) is a server-side integration that allows businesses to send conversion events — purchases, leads, add-to-carts, and custom actions — directly from their server to Meta's advertising platform. Unlike the Meta Pixel, which relies on JavaScript running in the visitor's browser, CAPI transmits event data through a server-to-server connection that is not affected by ad blockers, browser privacy restrictions, or network interruptions.
Meta designed CAPI to work alongside the pixel in what it calls "redundant event setup." The pixel captures what it can from the browser, CAPI sends the same events from the server, and Meta deduplicates them using an event ID. This ensures that even when the pixel is blocked, the conversion data still reaches Meta's optimization engine.
Why it matters
Browser-based tracking is losing ground. Safari's Intelligent Tracking Prevention caps cookie lifespans, ad blockers strip the Meta Pixel before it loads, and iOS App Tracking Transparency prompts have dramatically reduced the data available to Meta's algorithms. The consequences are direct: smaller retargeting audiences, degraded lookalike models, and underreported conversions that distort ROAS calculations.
CAPI addresses these gaps:
- Higher match rates — Server-side events can include hashed customer identifiers (email, phone, external ID) that the pixel cannot access, giving Meta more signals to match conversions to ad clicks.
- Ad blocker resilience — Events sent server-to-server never touch the browser, so they cannot be blocked.
- Better optimization — More complete conversion data means Meta's delivery algorithm can find higher-value audiences and exit the learning phase faster.
- Data control — Because events pass through your server first, you decide exactly what data is shared and can strip sensitive fields before transmission.
How it works
A typical CAPI integration follows this flow:
- Event capture — A user completes an action on your site (e.g., a purchase). Your server records the event along with available identifiers.
- Payload construction — The server builds a CAPI-formatted payload that includes the event name, event time, action source, user data parameters (hashed email, phone, IP, user agent), and a unique event ID for deduplication.
- Server-to-server transmission — The payload is sent via HTTPS POST to Meta's Graph API endpoint for the corresponding pixel ID.
- Deduplication — Meta matches the server event against any corresponding browser pixel event using the shared event ID, counting the conversion only once.
Key parameters for high match quality
| Parameter | Purpose | Impact |
|---|---|---|
em (email) |
Hashed email address | Primary identity matcher |
ph (phone) |
Hashed phone number | Secondary identity signal |
external_id |
Your internal user ID | Cross-session identity |
fbp |
Meta first-party cookie value | Links to pixel session |
fbc |
Facebook click ID from URL | Ties conversion to ad click |
event_id |
Unique per-event identifier | Prevents double-counting |
How Ingest Labs handles Facebook Conversions API
Ingest Labs includes Meta CAPI as a pre-built destination that requires no custom API integration or developer resources. Events captured by Ingest IQ are automatically enriched with identity signals — including the durable MPID cookie, hashed user data, and click IDs — then forwarded to Meta in the correct CAPI format with deduplication handled automatically. Most customers see match quality scores above 8.0 within the first week of deployment.
See how Ingest Labs handles facebook conversions api (capi)
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