If you have looked at your analytics or your browser address bar recently and seen ?utm_source=chatgpt.com stuck on the end of a URL, here is the short answer: somebody clicked a link inside ChatGPT to reach that page. The parameter is a tracking tag ChatGPT appends to its outbound links so that website owners can tell ChatGPT-referred visits apart from everything else.
The longer answer is more useful, because in October 2026 this parameter broke for a week, came back, and acquired a sibling — utm_medium=feed — that tells you something quite different about where the visitor came from.
Key takeaways
utm_source=chatgpt.commeans the visit came from a link clicked inside ChatGPT. It does not mean ChatGPT crawled you, scraped you, or ran an ad for you.- In our 21 October test, 96 of 97 outbound links carried it.
utm_medium=feedon top of it means the link came from a merchant product catalogue submitted to OpenAI, not from a crawled web page. In our test, 17 links carried it.- Between 8 and 15 October 2026 the parameter went missing. Visits from ChatGPT were logged as direct traffic. OpenAI confirmed a bug and fixed it on 15 October.
- Referrer is still not reliable, parameter or not: button-style entry points are opened with
noreferrer. - If you are a reader seeing this in your own address bar, it is harmless and you can delete everything from the
?onward.
What the parameter actually is
UTM parameters are a twenty-year-old convention for tagging inbound links so an analytics tool can group them. They are added by whoever creates the link, and they travel in the URL. utm_source names where the click came from.
So https://www.example.com/product/?utm_source=chatgpt.com decodes as: this visitor arrived by clicking a link that ChatGPT put in an answer.
Hovering a text buy link in a ChatGPT answer shows you the destination with the parameter attached — in the screenshot above, https://www.apple.com/macbook-air/?utm_s…, truncated by the hover card. Note that this only works for text links. Black buy buttons are buttons, not hyperlinks: you cannot hover them, and their context menu has no "Copy Link Address". We cover that distinction in the "Shop at" button.
The three parameters worth separating
Not every ChatGPT visit is the same kind of visit, and the parameters tell you which is which.
Parameter | What it tells you | How often we saw it |
|---|---|---|
| The click came from inside ChatGPT | 96 of 97 links |
| The destination came from a merchant catalogue submitted to OpenAI, not from a crawled page | 17 of 97 links |
| Same origin, seen on a catalogue-sourced buy button | Observed on an Anker SOLIX store link |
The second row is the one most teams are not yet splitting out, and it is the one that changes decisions. A visit with utm_medium=feed means your product data won the placement. A visit without it means your page won the placement. Those are two different teams, two different budgets and two different fixes. Feed-sourced placement is covered in the ChatGPT product feed; page-sourced placement is covered in how AI search picks sources.
The week the parameter disappeared
Between 8 and 15 October 2026, ChatGPT's outbound links stopped carrying utm_source and passed the HTTP referrer unreliably. Adobe's Cedric Huesler traced the cause: GPT-6 opened links with window.open(url, '_blank', 'noopener,noreferrer') and dropped utm_source=chatgpt in the process. With no parameter and no referrer, analytics had nothing to work with, so the visits landed in direct traffic.
Across roughly 500 pages, Huesler observed ChatGPT-attributed visits falling by about 31,000 a day while direct visits rose by about 26,000 a day. Those magnitudes are close enough to be the same people.
OpenAI never published a statement but confirmed it was a bug and fixed it on 15 October. utm_source=chatgpt.com returned.
The reporting trap. Over the same window, WISLR observed two stores whose ChatGPT-referred traffic appeared to drop 66% and 57% (9–13 October against 1–7 October). Set against Adobe's numbers, most of that is an attribution artefact, not lost business. Taking that week into a month-over-month comparison, a post-mortem or a KPI review will produce a confidently wrong conclusion.
What to do instead: put two annotation lines on your traffic reports, at 8 October and 15 October. Exclude the span between them. When comparing periods, compare across the gap rather than through it.
How to track ChatGPT traffic properly
A workable setup, in order:
- Identify the channel by parameter, not by referrer. In GA4, segment on
source = chatgpt.com. Do not build the rule on referring domain — button-type entry points send none. - Split catalogue traffic out. Add
medium = feedas a second dimension. Report page-sourced and feed-sourced visits separately; they respond to different work. - Annotate the 8–15 October gap and keep the annotation in place permanently. Anyone who pulls that quarter later will need it.
- Expect a floor, not a ceiling. Even with the parameter working, some ChatGPT-driven demand arrives untagged — people read an answer, then type your brand into a browser later. Treat tagged visits as the measurable fraction.
- Measure recommendation, not just clicks. Clicks are the bottom of the funnel. Whether you are being recommended at all is the thing upstream of them, and it is trackable as Share of Model across ChatGPT, Google AI Mode, Gemini, Google AI Overviews and Microsoft Copilot.
Step-by-step GA4 configuration, including the AI-referral channel group, is in how to track AI-referred traffic in Google Analytics 4.
If you are not a marketer: how to remove it
If you copied a link out of ChatGPT and want a clean URL, delete the ? and everything after it. https://example.com/page/?utm_source=chatgpt.com becomes https://example.com/page/. The page is identical — the parameter only exists for the site's analytics. It does not track you personally, it does not identify your ChatGPT account, and leaving it in place does nothing harmful.
FAQ
What does utm_source=chatgpt.com mean? It marks a visit that arrived by clicking a link inside ChatGPT. The parameter is added by ChatGPT to its outbound links so the destination site can attribute the visit.
Is utm_source=chatgpt.com safe? Does it track me? It is safe. It identifies the channel — ChatGPT — to the website you are visiting. It carries no account, conversation or personal identifier.
How do I remove utm_source=chatgpt.com from a URL? Delete the ? and everything following it before sharing or bookmarking the link.
Why did my ChatGPT traffic disappear in October 2026? Most likely it did not. Between 8 and 15 October the parameter was missing because of a bug, so those visits were recorded as direct traffic. OpenAI fixed it on 15 October. Exclude that week from comparisons.
What does utm_medium=feed mean? That the link came from a product catalogue the merchant submitted to OpenAI, rather than from a page ChatGPT crawled. It is a strong signal that your feed, not your website, won that placement.
Can I rely on the HTTP referrer instead? No. Many ChatGPT entry points are buttons opened with noreferrer, which send no referring domain at all. The UTM parameter on your landing page is the dependable signal.
Sources
The outage mechanism, the ~500-page observation and the daily figures are from Search Engine Roundtable, 14 October 2026, reporting observations by Adobe's Cedric Huesler. The two-store traffic drop is from WISLR, published 14 October 2026 and updated 16 October.
The parameter counts — 96 of 97 links carrying utm_source=chatgpt.com, 17 carrying utm_medium=feed, and the openai_catalog campaign value — are from GEOly Research: 28 shopping prompts run in a signed-out Chrome window on 21 October 2026, with every outbound link clicked and logged. The full method is in how ChatGPT shopping results work after GPT-6.
