fbclid

fbclid - the Facebook Click Identifier - is a parameter Meta appends to the destination URL when someone clicks a link on Facebook or Instagram, including ads. The visitor arrives with ?fbclid=IwAR... in the URL: an opaque token identifying the click event on Meta's side.

For advertisers, its value is matching. When a conversion is reported back to Meta - typically through the Conversions API - including the fbclid lets Meta tie the outcome to the specific click, and therefore to the campaign, ad set, and ad that produced it. As browser-side tracking has become less reliable, this server-side matching has become the sturdier half of Meta attribution, and the fbclid is one of the strongest match keys available.

Like every click identifier, it is fleeting. It exists only in the landing page URL and disappears on the next navigation, so a site that wants click-level Meta attribution has to capture the parameter on arrival and keep it until the visitor does something worth attributing - such as submitting a form several pages later. Notably, fbclid also rides on many organic Facebook clicks, so its presence signals a Facebook-originated visit even outside paid campaigns.

The SheetLink Forms embed captures fbclid automatically. sl.js reads it from the URL alongside gclid, wbraid, gbraid, msclkid, and the five UTM parameters, persists the values in localStorage across pages, and attaches them to every submission. Add a matching column to your sheet and each Meta-originated lead lands with its fbclid beside it, ready for a Conversions API upload or plain source reporting.

The capture mechanics are walked through in the guide on capturing gclid in forms - the same flow covers fbclid - and you can watch attribution columns fill on the live demo.