A click ID is a unique identifier that an ad platform automatically appends to your destination URL whenever someone clicks an ad. It is the link between the ad click and the conversion that follows.
How does a click ID work?
When someone clicks your Google or Meta ad, they do not land on plain example.com/offer. They land on a URL with an extra parameter, such as ?gclid=Cj0KCQ... or ?fbclid=IwAR.... Your tracking reads that value and stores it. When a lead or purchase happens later, the click ID is sent back to the platform together with the conversion event. The platform then knows: this conversion belongs to this click, this ad and this campaign.
The most common click IDs:
| Platform | Click IDs |
|---|---|
| Google Ads | gclid, gbraid, wbraid, gad_source, dclid |
| Meta | fbclid, _fbp (browser ID) |
| TikTok | ttclid, _ttp |
li_fat_id | |
| Microsoft Ads | msclkid |
| X (Twitter) | twclid |
| Snapchat | ScCid |
rdt_cid |
Why do click IDs matter?
With third-party cookies disappearing and Safari ITP capping cookie lifetimes, the click ID is often the most reliable signal for matching a conversion to a click. When click IDs get lost, for example because a redirect strips them or your form lives on another domain, signal loss goes up. Your campaigns look worse than they are, and the bidding algorithm has less data to learn from.
Click IDs sent through the Conversions API also improve Event Match Quality, because Meta can match the event to the click with more confidence.
Unlike UTM parameters, which you set yourself, click IDs are not human-readable. The two work together: UTMs describe the campaign for you, the click ID describes the click for the platform.
Click IDs with LeadSignal
LeadSignal automatically captures gclid, gbraid, wbraid, gad_source, dclid, fbclid, _fbp, ttclid, _ttp, li_fat_id, msclkid, twclid, ScCid and rdt_cid. Once marketing consent is given, they are tied to the person and shown in the lead list next to source and landing page, so you can see which ad click every lead came from. LeadSignal forwards conversions to Meta, Google Ads, LinkedIn and TikTok. For Microsoft Ads, Snapchat and Reddit the click IDs are stored, but conversions are not forwarded (yet).
See which platforms are connected on our integrations page.