This document describes how to send offline conversion events to the Yes We Track (YWT) endpoint so that online attribution can be linked to offline outcomes (sales, qualified leads, subscriptions). The examples use plain JSON and HTTP headers and can be called from your backend, CRM, or ESB.

1) Endpoint

Default pattern (single endpoint + event parameter):

https://ywt.<yourdomain>.nl/data?event_name=<event_name>

Where:

• <yourdomain> → your server side tagging domain.
• <event_name> → the event name (e.g., session_attribution, purchase, qualified_lead).

2) Required Inputs

2.1 Request Headers (include if available)

• x-forwarded-for → visitor IP address
• user-agent → browser user agent string
• Cookie header including the following cookies (if present):
  • FPID
  • _gcl_aw
  • _gcl_gb
  • _fbp
  • _fbc
  • li_fat_id
  • _uetmsclkid
  • FPGCLAW
  • _ga
  • _ga_<GA4_MEASUREMENT_ID>

Example headers (raw HTTP):

POST /data?event_name=session_attribution HTTP/1.1
Host: ywt.example.nl
Content-Type: application/json
x-forwarded-for: 203.0.113.42
user-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36
Cookie: FPID=fpid_abc123; _gcl_aw=GCLAW.1696162000.abc; _gcl_gb=GCLGB.1696162000.def; _fbp=fbp.1.1696162000.ghi; _fbc=fb.1.1696162000.xyz; li_fat_id=li_123; _uetmsclkid=uet_456; FPGCLAW=gclaw_789; _ga=GA1.2.1234567890.1696162000; _ga_G-ABCD1234=GS1.1.1696162000.1.0.1696162000.0.0.0

Example headers (cURL):

curl -X POST "<https://ywt.example.nl/data?event_name=session_attribution>"   -H "Content-Type: application/json"   -H "x-forwarded-for: 203.0.113.42"   -H "user-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36"   -H "Cookie: FPID=fpid_abc123; _gcl_aw=GCLAW.1696162000.abc; _gcl_gb=GCLGB.1696162000.def; _fbp=fbp.1.1696162000.ghi; _fbc=fb.1.1696162000.xyz; li_fat_id=li_123; _uetmsclkid=uet_456; FPGCLAW=gclaw_789; _ga=GA1.2.1234567890.1696162000; _ga_G-ABCD1234=GS1.1.1696162000.1.0.1696162000.0.0.0"   --data-binary @payload.json

2.2 User Data