Short answer
oppref is the click reference OpenAI appends to your landing page URL as ?oppref=…. The Pixel stores it in a first-party cookie, and you should pass it in Conversions API calls. If a redirect or navigation drops it, conversions may not be linked to the ad.
Where it gets lost
- 301/302 redirects that drop query strings
- Domain changes between landing page and checkout
- Forms on a different subdomain without the cookie
- Cookie consent declined before the Pixel can store it
Fix
- Test a click: confirm ?oppref= is present on landing
- Preserve query strings in redirect rules
- Store oppref in a hidden form field for lead forms
- Send it with server-side events
Questions
Is oppref personal data?
It is a click reference. Handle it under your normal consent and privacy notice.
Facts checked against the sources below on 12 October 2026. Platforms change quickly: if something here no longer matches what you see, tell us and we will update it.
