In short. utm_source=chatgpt.com labels the declared source of a visit, while attribution to a specific ChatGPT answer requires evidence beyond that editable tag.
Definition:
utm_source=chatgpt.comis a URL parameter that labels ChatGPT as the declared traffic source. In the archived copy of its publisher FAQ captured on 4 October 2026, OpenAI describes adding this parameter automatically to referral URLs from ChatGPT search results.
Key facts
- OpenAI's archived Publishers and Developers FAQ documents the parameter for tracking incoming ChatGPT search traffic in analytics tools.
- Google's campaign URL documentation defines
utm_sourceas the referrer label and allows parameters to be added manually. - Google's Traffic acquisition report documentation defines Sessions as sessions beginning on the website or application. A session count measures recorded site activity.
What does the parameter contain?
A UTM parameter is a name and value added to a destination URL for campaign measurement. As of 17 October 2026, Google's URL builders documentation explains that these values are sent to Analytics when someone clicks a referral link. In this parameter, utm_source is the name and chatgpt.com is the value.
The following illustrative URL combines Google's documented URL syntax with the source value documented by OpenAI:
https://www.example.com/?utm_source=chatgpt.com
The question mark begins the parameters. An ampersand separates additional parameter-value pairs. The same Google documentation treats utm_medium, the marketing medium, and utm_campaign, the campaign name, as separate fields. The source label alone supplies neither value.
What can a tagged visit establish?
Google's manual tagging documentation maps utm_source to manual source dimensions, including Session manual source. Since the sender can choose the value, the parameter alone cannot authenticate a ChatGPT click or identify the answer containing the link. This is a limit of using an editable URL label as evidence of origin.
OpenAI's archived FAQ ties the parameter to inbound traffic from search results. The archive establishes the published description on its capture date; current automatic tagging remains unverified here.
For measurement, the distinction follows from Google's Sessions definition: a session begins with activity on the website or application. Counting tagged sessions therefore cannot count citations that produce no website visit.
How is the source checked in analytics?
Google's Traffic acquisition instructions place the report under Reports, then Acquisition, then Traffic acquisition. The report includes Session source and a search bar for finding a traffic source. Selecting Session source and searching for chatgpt.com checks the source assigned to recorded sessions.
Google's traffic-source scopes documentation explains that Session dimensions describe acquisition when new sessions begin, including returning visitors. First user dimensions retain the source associated with a user's initial acquisition. Those scopes answer different measurement questions, so comparing their counts requires attention to the selected dimension.
Related terms
- UTM parameters
- AI referral traffic
- GA4 traffic acquisition
- How do I find ChatGPT referral visits in GA4?
FAQ
Why does the parameter disappear from my landing-page report?
Google's URL builders documentation says UTM parameters are omitted from Landing page + query string and Page path + query string. You can inspect Page location for that information instead.
Why can my first-user source differ from my session source?
Google's scope definitions keep the first-user value as a person returns, while session values describe acquisition for new sessions. You can therefore see different sources for the same returning visitor across those dimensions.
Sources
- OpenAI, "Publishers and Developers - FAQ", archived 4 October 2026
- Google Analytics Help, "URL builders: Collect campaign data with custom URLs", accessed 17 October 2026
- Google Analytics Help, "Traffic-source dimensions, manual tagging, and auto-tagging", accessed 17 October 2026
- Google Analytics Help, "[GA4] Traffic acquisition report", accessed 17 October 2026
- Google Analytics Help, "Scopes of traffic-source dimensions", accessed 17 October 2026
Check how a page reads to answer engines. Open the GEO score analyzer