The fbclid (Facebook Click Identifier) is Meta's click ID. It gets appended to links clicked on Facebook and Instagram and lets Meta tie a later lead or purchase back to the original click.
How does the fbclid work?
When someone clicks your link on Facebook or Instagram, Meta adds a parameter to the URL:
https://example.com/offer?fbclid=IwAR2xV8kLmN...
The Meta Pixel reads the value and stores it as the first-party cookie _fbc. It also sets _fbp, a browser ID that exists even without an ad click. When a conversion event fires later, the pixel sends both values to Meta. With the Conversions API you can send the same values from your server.
Why does the fbclid matter?
The fbclid is one of the strongest signals Meta uses to match an event to a person, and it feeds directly into Event Match Quality. The more events arrive with an fbclid and hashed contact details, the better Meta can optimize your campaigns.
Common reasons the fbclid gets lost:
- Ad blockers stop the pixel from loading and setting the cookie
- Safari ITP shortens cookie lifetimes
- Redirects or form tools on third-party domains drop the parameter
- Without marketing consent, the cookie must not be set
This is where server-side tracking helps: once the fbclid has been captured, your server can reliably send it with the event, even when the pixel is blocked in the browser.
fbclid with LeadSignal
LeadSignal captures fbclid and _fbp automatically and stores them per session. With consent, they are tied to the person, so the lead list shows you which leads came from Meta. Your conversions reach Meta on two paths in parallel: in the browser through the Meta Pixel and server-side through the Conversions API, deduplicated with a shared event ID. Combined with hashed email and phone, this lifts your Event Match Quality without a developer or Google Tag Manager.
For a step-by-step walkthrough, read our Meta Conversions API setup article.