AI referral sources: hostnames and UTM values

This is how TraceLog classifies where a session came from in its own record. It describes no other tool and states no traffic figure.

How a visit is matched

TraceLog compares each value in the table, ignoring case, with the host of the referrer and with the link's utm_source. A host value also matches every host under it: chatgpt.com matches www.chatgpt.com too. Any other value has to match whole.

An assistant's rule is read before a search engine's, so a visit from gemini.google.com counts as Gemini, not as Google search.

Two things on the link come first:

• The medium. utm_medium=email counts as email, whatever the source says.
• A paid signal. A paid medium such as utm_medium=cpc, or a click identifier an ad platform adds, such as oppref on an ad in ChatGPT, makes the visit paid. A paid visit from any assistant in the table counts as Other paid, and names no assistant.

Version 7, released Nov 11, 2026

What changed: a return from a payment processor, or a visit referred by the site's own pages, counts as Unknown origin instead of Direct. No AI rule changed.

Earlier versions

A session keeps the version that classified it, so a visit recorded under an earlier one keeps its channel.

• Version 6, Nov 9, 2026. No rule changed: Google's numeric campaign ID fills the campaign when the link names none.
• Version 5, Nov 5, 2026. ChatGPT's Android app, com.openai.chatgpt, counts as ChatGPT; utm_source=google_ai_mode counts as Google AI Mode; and Gmail's Android app counts as email.
• Version 4, Sep 30, 2026. An ad clicked in an assistant counts as paid, and OpenAI's oppref marks a paid click.
• Version 3, Sep 20, 2026. Paid media and click identifiers became rules of the version, beside Meta's fb, ig and meta and email and SMS as a source. No AI rule changed.
• Version 2, Aug 26, 2026. A return from a payment processor or a hosted checkout counts as Direct, not as a referral. No AI rule changed.
• Version 1, Aug 18, 2026. ChatGPT, Claude, Perplexity, Gemini and Copilot, each by its host and by its name as a source.

What this list does not cover

• AI answers inside a search engine. A click in an AI Mode answer arrives from google.com and counts as organic search. Only a source on the link, as in Google AI Mode and Gemini carts, names it.
• A visit with no referrer and no source. An app that sends neither leaves nothing to match, and the visit counts as Direct.
• Sessions already recorded. A new version classifies the visits that arrive after it, and never rewrites the ones before.

So a count of sessions from AI assistants is a floor: what is confirmed, never an estimate.