How do I track traffic from ChatGPT in Google Analytics 4?

Why ChatGPT visits hide in your reports

GA4 decides where a visit came from by two things: the UTM tags in the landing URL and the referrer the browser sends. ChatGPT traffic often has only the first. On our sample site, 79% of ChatGPT visitors arrived with utm_source=chatgpt.com in the link and no referrer at all (own measurement, 21 to 27 September 2026; see the case study). Visits from the apps, copied links and some browsers lose the referrer; visits without the tag either then look like Direct traffic.

We looked for an OpenAI page describing the tag on 15 October 2026 and couldn’t find a current one, so treat it as observed behavior, not a promise. The rule we use everywhere is simple: a visit is ChatGPT if the referrer is chatgpt.com or the link carries utm_source=chatgpt.com.

Step 1: check the built-in AI Assistant channel

GA4 added an “AI Assistant” channel to the Default Channel Group on 13 May 2026 (GA4 What’s new, read 15 Oct 2026). Google describes it as visits “from sources like ChatGPT, Gemini, Deepseek, Copilot, or Grok”, assigned when the medium is ai-assistant or the referrer matches its list of assistants, and it excludes AI Overviews and AI Mode (GA4 default channel group, read 15 Oct 2026). Google doesn’t publish the list on that page.

1. Go to Reports, Acquisition, Traffic acquisition.
2. Set the table to “Session default channel group” and look for AI Assistant.
3. Switch the dimension to “Session source / medium” and search for chatgpt.

If you see chatgpt.com rows outside AI Assistant (in Unassigned, Referral or elsewhere), the built-in channel isn’t catching them, and Step 2 fixes that for your reports.

Step 2: add a custom channel group by source

Google’s own steps (GA4 custom channel groups, read 15 Oct 2026):

1. Admin, Data display, Channel groups (Editor access needed). Create a new channel group.
2. Add a channel named “AI assistants” with the condition Source matches regex and the pattern below.
3. Save, then reorder so “AI assistants” sits above Referral, as Google advises. Traffic goes to the first channel it matches.
4. Pick the new group as the primary dimension in Traffic acquisition.

Google says custom channel groups apply to your reports retroactively, so you see past ChatGPT traffic too. Standard properties can have 2 custom groups.

Example: the regex

Google’s help page offers a broad pattern built from pieces like .*gpt.* and .*gemini.*, which can catch any source that merely contains those letters. This one names hosts exactly and works whether GA4 matches the whole value or part of it:

^(.*\.)?(chatgpt\.com|openai\.com|perplexity\.ai|claude\.ai|gemini\.google\.com|copilot\.microsoft\.com|copilot\.com|chat\.deepseek\.com|grok\.com)$

Add a host when you see a new assistant in your source list. If you tag your own links in AI tools, use utm_medium=ai-assistant and Google’s channel picks them up too.

Step 3: read the numbers that matter

• Landing pages: add “Landing page” as a secondary dimension. On our sample site, 59% of ChatGPT visitors landed on two pages written for a customer’s situation (own measurement, first week).
• Key events: compare sign-ups or purchases per session for AI assistants with other channels. Small numbers swing a lot; read weeks, not days.
• Direct: if Direct grows when AI assistants grow, some untagged AI traffic is probably in there. You can’t recover it in GA4.

What GA4 can’t see

• Bots. GPTBot, OAI-SearchBot and ChatGPT-User don’t run your analytics script. Count them in server or CDN logs.
• Mentions without a click. For that, see how to track brand mentions in AI answers and how to check if ChatGPT recommends you.
• Google’s AI features. They count as Google organic. Search Console’s Generative AI performance report covers them.

What Katman does here

Katman is an MCP server that runs inside your AI coding tool. katman_generate returns an analytics snippet that applies the ChatGPT rule above and a human filter, plus a server-side bot counter for Cloudflare Workers, Next.js, Express, Astro or SvelteKit, so crawler visits are counted where analytics can’t see them. Your coding tool adds them; Katman doesn’t touch your GA4 property. Katman Pro is $99 a month for up to 3 sites, with fix prompts and page briefs uncapped. Or have us do it: Growth writes 30 pages a month for you. More on the measure step of the method.

Written by the Katman team, Rnify Limited. Google Analytics Help pages checked 15 October 2026; sample-site figures from the site’s own analytics, human sessions only (528 of 1,546), 21 to 27 September 2026, one sample site, our own product.