Meta Ads Conversions API (CAPI) Server-Side Tracking Webhook

Overview

This workflow provides a complete server-side endpoint for sending conversion events to the Meta (Facebook) Conversions API (CAPI). It solves the critical problem of ad tracking accuracy in an era where browser-based tracking is increasingly blocked by ad blockers, iOS privacy changes (ATT), and browser cookie restrictions. By sending conversion data directly from your server to Meta's servers, you bypass these client-side limitations and ensure your ad performance data remains reliable and complete.

The workflow receives incoming webhook data (typically from a website form submission or backend system), normalizes and hashes personally identifiable information (PII) using SHA-256 as required by Meta, structures the payload according to Meta's CAPI specifications, and sends it to the Graph API endpoint. It also returns a 200 response to the caller to confirm successful processing.

Workflow Steps

1. Webhook (No auth) — This is the trigger node that receives incoming HTTP POST requests. It listens on the path /meta-conversion-api and expects a JSON body with user data including email, phone, firstName, lastName, fbc, and fbp. The node is configured to respond using a separate "Respond to Webhook" node rather than automatically.

2. Edit Normalize PII (No auth) — A Set node that cleans and normalizes incoming PII data. It trims whitespace, converts email and names to lowercase, and strips all non-digit characters from the phone number. This creates standardized fields (normalized_email, normalized_phone, firstName, lastName) for consistent hashing.

3. Crypto - Hash Email (No auth) — Uses SHA-256 hashing on the normalized email address. The result is stored in a field called hashed_em, which is the format Meta expects for email identifiers.

4. Crypto - Hash Phone (No auth) — Uses SHA-256 hashing on the normalized phone number. The result is stored in hashed_ph, matching Meta's expected phone identifier format.

5. Crypto - First Name (No auth) — Uses SHA-256 hashing on the normalized first name. The result is stored in hashed_firstName, which will be mapped to Meta's fn field.

6. Crypto - Last Name (No auth) — Uses SHA-256 hashing on the normalized last name. The result is stored in hashed_lastName, which will be mapped to Meta's ln field.

7. Set - Compute Timestamps & Map Fields (No auth) — A Set node that assembles all the processed data into a unified object. It computes a Unix timestamp for the current time, hardcodes the event name as SubmitApplication (configurable), and pulls together all hashed fields plus the original fbc, fbp, IP address (from x-forwarded-for header), and user agent from the webhook headers.

8. Preparing for HTTP Request Payload (No auth) — A Code node that transforms the flat data into Meta's required CAPI payload structure. It creates a data array with an object containing event_name, event_time, action_source (set to website), and a user_data object mapping the hashed fields to Meta's field names (fn, ln, em, ph, fbc, fbp, client_ip_address, client_user_agent).

9. Sending Events To Facebook Pixel (Bearer Token auth) — An HTTP Request node that sends the final payload to Meta's Graph API endpoint at https://graph.facebook.com/v24.0/PIXEL_ID_HERE/events. It uses Bearer Token authentication with a CAPI access token. The URL contains a placeholder PIXEL_ID_HERE that must be replaced with the user's actual Meta Pixel ID.

10. Respond to Webhook (No auth) — Returns a 200 HTTP response to the original webhook caller with the processed data, confirming successful delivery to Meta.

Setup Instructions

Prerequisites

• A Meta (Facebook) Pixel with Conversions API access
• A Meta CAPI Access Token generated from Events Manager
• An n8n instance (self-hosted or cloud) with webhook capability
• A website or backend system that can send HTTP POST requests

Configuration Steps

1. Copy the Webhook URL: Open the "Webhook" node and copy the Test URL (for testing) or Production URL (for live use). Configure your website form or backend to send a POST request to this URL with a JSON body containing the required fields.

2. Customize Event Name (Optional): In the "Set - Compute Timestamps & Map Fields" node, change the event_name value from SubmitApplication to your desired event type (e.g., Purchase, Lead, CompleteRegistration, AddToCart).

3. Add Your Pixel ID: In the "Sending Events To Facebook Pixel" node, replace PIXEL_ID_HERE in the URL with your actual Meta Pixel ID (a numeric string found in Meta Events Manager).

4. Add Your Access Token: In the same node, go to the Authentication tab and create a new Bearer Token credential. Paste your CAPI Access Token (generated from Meta Events Manager > Settings > Conversions API > Generate Access Token).

5. Test the Workflow: Use a tool like Postman or curl to send a test POST request with sample data matching the pinned data structure on the Webhook node. Activate the workflow and verify you receive a 200 response with events_received: 1.

Use Cases and Variations

Primary Use Cases

• Lead Generation Forms: Send lead form submissions from your website directly to Meta for better conversion attribution
• Purchase Tracking: Change the event name to Purchase and include value and currency fields for revenue tracking
• Add to Cart / Initiate Checkout: Track micro-conversions that indicate purchase intent
• Complete Registration: Track user signups that happen on your platform

Adaptation Ideas

• Add Value Tracking: Modify the Code node to include event_source_url, value, and currency fields for purchase events
• Multiple Event Types: Add conditional logic to route different webhook payloads to different event names based on a field in the incoming data
• Error Handling: Add an error workflow or notification node (e.g., Slack, email) if the Meta API returns an error
• Data Enrichment: Add an HTTP Request node to look up additional user data from your CRM before sending to Meta
• Batch Events: Modify the Code node to accept an array of events in the webhook payload for batch processing
• Custom Action Sources: Change action_source from website to email, app, or phone_call depending on your conversion source

{
  "id": "mXgQJT7qXMEFQAow",
  "meta": {},
  "name": "Server-Side Meta Ads Tracking Template [PUBLIC]",
  "tags": [],
  "nodes": [
    {
      "id": "de88e89c-acfd-4592-8f73-0f1b56dba93b",
      "name": "Edit Normalize PII",
      "type": "n8n-nodes-base.set",
      "position": [
        -752,
        0
      ],
      "parameters": {
        "options": {},
        "assignments": {
          "assignments": [
            {
              "id": "9545094c-a24a-4689-b212-4bc351f8f08b",
              "name": "normalized_email",
              "type": "string",
              "value": "={{ $json.body.email.trim().toLowerCase() }}"
            },
            {
              "id": "fe26118b-5e9e-4c3f-acf0-e995a32779d1",
              "name": "normalized_phone",
              "type": "string",
              "value": "={{ $json.body.phone.replace(/\\D/g, '') }}"
            },
            {
              "id": "59a2b784-44c4-44c4-bf28-2e8a27cc8975",
              "name": "firstName",
              "type": "string",
              "value": "={{ $json.body.firstName.trim().toLowerCase() }}"
            },
            {
              "id": "72ada7ed-e895-445e-ac4f-f5d8102ba46a",
              "name": "lastName",
              "type": "string",
              "value": "={{ $json.body.lastName.trim().toLowerCase() }}"
            }
          ]
        }
      },
      "typeVersion": 3.4
    },
    {
      "id": "cf2debc3-7cc0-450f-9e58-9b981333c537",
      "name": "Crypto - Hash Email",
// ... truncated (copy to see full JSON)