Click IDs

What are click IDs?

A click ID is a unique value an ad platform appends to the landing page URL when someone clicks an ad. Google Ads adds gclid (and on some iOS traffic, gbraid or wbraid), Meta adds fbclid, Microsoft Ads adds msclkid, and TikTok adds ttclid.

The value identifies one specific click. When a conversion is later reported with that value, the platform knows exactly which ad, campaign and click it came from.

Why capturing them matters

Click IDs only exist in the URL of the landing page. If your site doesn't read and store them on that first page view, they're gone once the visitor navigates away. Redirects that strip query strings, forms that don't carry them forward, and single-page apps that rewrite the URL all lose them.

For server-side tracking the click ID is often the strongest match key you have. A conversion uploaded to Google Ads with the right gclid can be attributed directly; without it, the platform has to fall back on hashed email or phone, if you sent them.

How click IDs relate to cookies

Platform scripts usually store the click ID in a first-party cookie. Meta's pixel writes the _fbc cookie from fbclid, and Google's tag stores gclid in its own cookies. Server-side events read these values so the conversion carries the click ID even if it happens days later.

Safari's tracking protections can shorten cookie lifetimes and, in some browsing modes, strip known click ID parameters from URLs, which is one reason capture on the first hit matters.

How TracerKit handles it

TracerKit captures click ids on the landing hit, including gclid for Google Ads, fbc and fbp for Meta, and ttclid and ttp for TikTok. When a conversion arrives later, including from a Stripe, Typeform or Calendly webhook, it's joined to the visitor's profile so those ids go out with the server-side event.