---
title: Conversion API Implementation — GTM Server-Side Module 3 — RGM Training
url: https://realgrowthmatters.com/training/gtm-server-side/conversion-api-implementation/
updated: 2026-06-10
source_html: https://realgrowthmatters.com/training/gtm-server-side/conversion-api-implementation/
---

RGM° · Training

# Conversion API Implementation

CAPI lets advertisers send conversion data server-to-server, bypassing browser-pixel limitations. This module covers Meta CAPI, Google EC, and the patterns that produce 10 - 50% more measured conversions.

### What you will learn

1. What Conversion API is and why every paid-media program needs it
2. Meta Conversions API: the canonical implementation
3. Google Enhanced Conversions and Conversion API
4. TikTok Events API, LinkedIn CAPI, Snap CAPI
5. The event-quality match-quality score
6. Customer data and hashed identifiers
7. Event deduplication: pixel + API both
8. Click identifier (CLID/FBCLID/GCLID) handling
9. Common CAPI mistakes
10. CAPI for offline conversions
11. Measurement and validation

## 1. What CAPI does

Conversion API (CAPI) lets advertisers send conversion data directly from server to ad platform, bypassing the browser-pixel limitations of client-side tracking. Result: 10 - 50% more conversions reported, higher match rates, better campaign optimization.

## 2. Meta Conversions API

The canonical implementation. Server sends events to Meta's API endpoint with: event name, event time, user\_data (hashed identifiers), custom\_data (value, currency, content\_ids), action\_source, event\_id (for deduplication).

## 3. Google's versions

- **Enhanced Conversions for web:** Adds hashed user data to existing client-side conversions.
- **Enhanced Conversions for leads:** Server-to-server for offline conversions.
- **Conversion Linker:** Solves cross-domain attribution in privacy-restricted browsers.

## 4. Other platforms

- **TikTok Events API.**
- **LinkedIn CAPI.**
- **Snap CAPI.**
- **Pinterest CAPI.**
- **Reddit CAPI.**
- All similar conceptually; specifics differ.

## 5. Match quality

Meta's Event Match Quality score (0 - 10) reflects how well your events match Meta's identity graph. Higher match quality = better attribution and optimization. Improve by sending: email (hashed), phone (hashed), first/last name (hashed), city, state, zip, country, IP, user agent, click identifiers.

## 6. Hashed identifiers

SHA-256(normalized email) where normalized = trim + lowercase

Same hashing applies to phone (E.164 format), names (lowercase, no punctuation), and other identifiers.

## 7. Deduplication

Most implementations send the same event via pixel AND CAPI for redundancy. To prevent double-counting:

- Use the same event\_id in both pixel and CAPI.
- Send within the deduplication window (typically 48 - 168 hours).
- Use consistent event names.

## 8. Click identifier handling

- **FBCLID** (Meta click identifier): capture from URL parameter, store in first-party cookie, send with CAPI events for 7+ days.
- **GCLID** (Google click identifier): same pattern.
- **TTCLID, LICLID, etc.**: each platform has its own.

## 9. Common mistakes

Not hashing user data correctly. Missing event\_id for deduplication. Sending raw PII. Failing to forward click identifiers. Not implementing for all key conversion events. Setting up but not monitoring.

## 10. Offline conversions

CAPI is the bridge from CRM / EHR / call-center conversions to digital ad platforms. Send conversion data with the original click identifier or hashed customer match to attribute.

## 11. Validation

- Meta Test Events tool.
- Server-side container preview mode.
- Vendor diagnostics dashboards.
- Compare CAPI-only vs pixel-only to confirm deduplication.
- Monitor match quality over time.

**How to use this module:** The Meta CAPI structure (Section 2), the deduplication pattern (Section 7), and the validation checklist (Section 11) are the planning artifacts.

### Sources & further reading

- [Meta Conversions API docs](https://developers.facebook.com/docs/marketing-api/conversions-api)
- [Google Enhanced Conversions](https://support.google.com/google-ads/answer/9888656)
- [TikTok Events API](https://ads.tiktok.com/help/article/events-api)
- [LinkedIn CAPI](https://www.linkedin.com/help/lms/answer/a1665692)
- [Simo Ahava on CAPI](https://www.simoahava.com/analytics/server-side-tagging-google-tag-manager/)
- [Stape CAPI articles](https://stape.io/blog/category/conversion-api)
- [measure.dev articles](https://measure.dev/)
- [MeasureSchool Meta CAPI](https://www.measureschool.com/facebook-conversion-api/)
- [WPMasterDev tracking blog](https://wpmasterdev.com/blog/)
- [Data & Business blog](https://www.dataandbusiness.com/blog/)
- [Shopify CAPI guides](https://help.shopify.com/en/manual/promoting-marketing/analyze-marketing/conversion-tracking)
- [HubSpot CAPI blog](https://blog.hubspot.com/marketing/conversion-api)

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Part of the [GTM Server-Side](/training/gtm-server-side/) series · RGM Training