Glossary · MeasurementTOFU
Conversions API (CAPI)
The short answer
The Conversions API (CAPI) is Meta's server-to-server connection that lets you send conversion events directly from your server to Meta, instead of relying only on the browser pixel.
Browser pixels miss events — ad blockers, browser privacy features, in-app browsers and patchy connections all interfere. CAPI fills those gaps, so Meta's algorithm sees more of the conversions that actually happened and can optimise better.
How it works with the pixel
- The browser pixel fires an event with a unique event ID.
- Your server sends the same event with the same event ID via CAPI.
- Meta deduplicates them and counts the conversion once.
- Additional customer information (hashed email, phone) improves event match quality.
What improves results
- Correct deduplication with shared event IDs
- Hashed customer parameters — email, phone, name, city — where consent allows
- Purchase values matching your back end
- Events sent promptly, not batched days later
- Monitoring event match quality in Events Manager
Ways to implement Conversions API
| Method | Best for |
|---|---|
| Platform integration (e.g., Shopify, WooCommerce plugins) | Small and mid-size stores |
| Server-side Google Tag Manager | Brands with multiple platforms |
| Direct API integration | Custom stacks and offline events |
| CRM or partner integrations | Lead outcomes and offline conversions |
See server-side tracking.
The Conversions API in practice
A store sends purchase events from its server to Meta alongside the browser pixel, with matching event IDs for deduplication. Meta sees more complete conversion data and optimises better.
Setup essentials
- Send key events server-side
- Deduplicate with event IDs
- Include customer information parameters with consent
- Monitor Event Match Quality
Common Conversions API mistakes
- Missing deduplication, double-counting conversions
- Sending events without consent where required
- Poor Event Match Quality from missing parameters
Frequently asked questions
Do we still need the pixel if we use CAPI?
Yes — run both, deduplicated. Each catches events the other misses.
Is CAPI compliant with privacy law?
It must be implemented with appropriate consent and data minimisation. Server-side doesn't exempt you from consent requirements.
What is event match quality?
Meta's score for how well events can be matched to users, based on the customer information sent. Higher is generally better for optimisation.
Can CAPI send offline events?
Yes — CRM and offline outcomes such as qualified leads or delivered orders can be sent as events.
Does the Conversions API replace the pixel?
Usually they work together, with deduplication.
Is the Conversions API hard to set up?
Many platforms offer integrations; custom setups need developer or partner help.
Does CAPI improve ad performance?
Often — better data helps optimisation, especially when browser tracking is limited.
Related terms
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