GCLID

GCLID (Google Click ID) is Google's universal attribution token. When someone clicks a Google Ads ad, Google appends a unique identifier (?gclid=ABC123) to the landing page URL. This ID is permanent to that click and encodes the keyword, ad, campaign, search term, device, and timestamp.

For online conversions (form submissions, purchases), Google uses the GCLID to close the attribution loop automatically. But phone calls happen offline, outside of Google's first-party tracking. DNI platforms like CallMatrix intercept the GCLID from the landing page URL and store it with the call. Later, you can upload the call as a conversion back to Google Ads, and Google matches it to the original click using the GCLID.

This unlocking of call attribution is transformative for phone-dependent industries. A law firm running Google Ads can now tell Google: 'Keyword personal injury lawyer near me generated 47 calls this month, 8 converted to cases, total case value $250K.' Google's bidding algorithm learns from this and optimizes keyword bids automatically.

GCLID is available on desktop and most Android traffic. On iOS, Apple's limitations mean GCLID is sometimes dropped. For those users, Google provides two fallback IDs: gbraid (Google Brand Retail Identifier for iOS app-bound traffic) and wbraid (for iOS web-only traffic). Together, these three IDs cover all Google Ads traffic.