utm_source=chatgpt.com is a tracking tag that ChatGPT adds to the links in
its answers. When someone clicks a source in a ChatGPT response, the URL they
land on ends in ?utm_source=chatgpt.com, and that tag is how Google
Analytics and every other analytics tool knows the visit came from ChatGPT.
It is not malware, it does not track the person clicking, and it does not
change the page they see. OpenAI describes it plainly in its publishers
FAQ:
ChatGPT "automatically includes the UTM parameter utm_source=chatgpt.com in
referral URLs, enabling clear tracking and analysis of inbound traffic from
ChatGPT search results."
If you found it in a link a friend sent you, they copied that link out of a ChatGPT answer. If you found it in your analytics, ChatGPT sent you a visitor. And if you stopped finding it in mid-October 2026, you were not imagining it — it disappeared for about a week. All three are covered below.
| Question | Short answer |
|---|---|
| What is it? | A UTM tag ChatGPT appends to outbound links so analytics can attribute the visit. |
| Is it safe? | Yes. It's a plain URL parameter with no code attached. |
| Which links get it? | Citations since ChatGPT search launched (Oct 2024); "More" source links since June 2025. |
| Does it affect SEO? | No, as long as your pages have a canonical tag. |
| Should site owners strip it? | No. It's often the only signal that a visit came from ChatGPT. |
| Why did it vanish in October 2026? | A bug after GPT-6; tagging returned on 15–16 October. |
| Does all ChatGPT traffic carry it? | No. A large share still lands as "Direct." |
What does utm_source=chatgpt.com mean?
It means the visitor arrived by clicking a link inside ChatGPT. UTM
parameters are a decades-old marketing convention — utm_source,
utm_medium, utm_campaign — that analytics tools read from the URL to
label where a visit came from. ChatGPT sets only the first one, with the value
chatgpt.com. It adds no medium and no campaign.
That missing utm_medium has a practical consequence: Google Analytics 4
needs a medium to sort a visit into a channel, so a visit tagged with only a
source can end up in Unassigned rather than Referral, as
SearchPilot documented in May 2026.
If your GA4 shows a block of chatgpt.com / (not set) sessions sitting in
Unassigned, this is why.
Which ChatGPT links get the tag?
Tagging started with citation links, the numbered sources inside an answer, around the launch of ChatGPT search on 31 October 2024. Seer Interactive reported at the time that citations carried the tag, while links elsewhere in search results often did not.
On 13 June 2025 OpenAI extended it to the links in the "More" sources section, which had previously gone out untagged — PPC Land covered the change after SEO consultant Glenn Gabe spotted it. Some articles date the start of tagging to June 2025; that is the "More" link change, not the beginning.
Links opened from ChatGPT Atlas, OpenAI's browser, are less consistent.
Independent tests have recorded them as chatgpt.com / referral, as Direct,
and as (not set), varying from site to site, so do not assume Atlas
traffic is tagged.
Why did utm_source=chatgpt.com disappear in October 2026?
Because of a bug that shipped with GPT-6. From about 8–9 October 2026, ChatGPT's new answer interface opened links without the tag and without a referrer, so the visits landed in analytics as Direct. OpenAI fixed it on 15 October, and tagged links were back at normal levels by the morning of 16 October (UTC).
The timeline is well measured, even though OpenAI has not published a word about it:
- Search Engine Roundtable broke the story on 14 October, citing Cedric Huesler of Adobe. Across about 500 pages where ChatGPT normally drove at least 5% of visits, he measured ChatGPT visits falling by roughly 31,000 a day while Direct rose by about 26,000 a day — the traffic had not gone away, it had lost its label.
- Profound tracked the share of ChatGPT answers containing at least one tagged link: about 98.5% on 8 October, about 75% on 9 October, as low as 5–12% on 14 October, and about 99% again by 06:30 UTC on 16 October.
- LLM Pulse saw daily ChatGPT sessions drop about 46% across the sites it monitors on 9–11 October, while those sites' total traffic fell only about 2%.
Huesler later said OpenAI told him privately that it was a known bug, and Search Engine Roundtable's 15 October update quotes him: "It was a bug. ChatGPT is tagging its links with utm_source=chatgpt.com again." We found no public statement from OpenAI, and no credible report of the tags disappearing again after 16 October.
What to do about it: nothing can recover the attribution for those days. Add an annotation to your GA4 property covering 8–16 October 2026, so that nobody reads the dip in ChatGPT traffic and matching bump in Direct as a real change, and exclude that week from any before/after comparison.
Why does ChatGPT traffic still show up as Direct?
Because the tag only works when ChatGPT adds it and the browser keeps it, and several common paths lose it — or lose the referrer that would otherwise identify the visit:
- Paid accounts. In Ahrefs' testing,
inline links in a paid ChatGPT account carried
noreferrer, while the same link in a free account did not. - Mobile apps. In-app browsers on iOS and Android strip the referrer.
- Copy and paste. A URL pasted into a new tab never carries a referrer, and it only keeps the tag if the person copied the whole URL.
- HTTP pages. ChatGPT's referrer policy drops the referrer when a link points to a non-HTTPS page.
Published estimates of how much AI-assistant traffic lands as Direct range from 35% to 70%, according to Patrick Stox's review of the available studies, with the top of that range coming from a vendor's own data. Treat whatever GA4 reports for ChatGPT as a floor, not a total.
How do you see ChatGPT traffic in Google Analytics 4?
Start with the built-in channel, then add a custom one to catch what it misses. On 13 May 2026 Google added an AI Assistant default channel to GA4. It is applied automatically when the referrer matches a recognised AI assistant, it needs no setup, and it does not apply to data from before that date. Its current definition names ChatGPT, Gemini, Deepseek, Copilot and Grok.
The built-in channel has a known gap: a session that arrives with only
utm_source=chatgpt.com and no referrer still falls into Unassigned, as
Search Engine Journal showed in July
2026.
To catch it, build your own channel:
- In GA4, open Admin → Data display → Channel groups and choose Create new channel group (you need Editor access).
- Add new channel, name it "AI assistants," and set the condition Source matches regex to the pattern below.
- Drag the channel above Referral. GA4 assigns a visit to the first channel it matches, so a new channel at the bottom never receives anything.
- Save, then pick the new group from the channel dropdown in Reports → Acquisition → Traffic acquisition.
A pattern that covers the major assistants:
chatgpt\.com|chat\.openai\.com|perplexity\.ai|claude\.ai|gemini\.google\.com|copilot\.microsoft\.com|deepseek\.com|grok\.com|meta\.ai|chat\.mistral\.ai|you\.com|poe\.com
Standard GA4 properties allow two custom channel groups, so this costs one of
them. For a one-off check without building anything, open Traffic
acquisition, switch the dimension to Session source / medium, and search
for chatgpt.
Do other AI assistants tag their links?
No. ChatGPT is the only major assistant that adds a UTM tag. The others rely on the referrer header, which some of their apps strip. The table summarises independent tests from 2025 and 2026; none of these companies documents the behaviour itself.
| Assistant | UTM tag | Referrer sent | Usually lost from |
|---|---|---|---|
| ChatGPT | utm_source=chatgpt.com | Sometimes | Paid accounts, mobile apps |
| Perplexity | None | perplexity.ai | The desktop app; some mobile visits |
| Claude | None | claude.ai on the web | The apps |
| Gemini | None | gemini.google.com | Deep Research links, most mobile app visits |
| Copilot | None | Intermittent | Copilot in Windows |
| Google AI Overviews / AI Mode | None | Counted as Google organic | Cannot be separated in GA4 |
Google is the special case: its own GA4 documentation puts AI Overviews and AI Mode clicks in Organic Search, not the AI Assistant channel, so a visit from an AI Overview is indistinguishable from an ordinary Google click.
Should you remove utm_source=chatgpt.com from your URLs?
If you are a site owner, no. Don't strip the tag, redirect it away, or block it. When the referrer is missing — which, as above, is often — the tag is the only evidence a visit came from ChatGPT, and removing it moves those visits straight back into Direct.
There is also no SEO reason to remove it. A UTM tag is just a URL parameter,
and Google's duplicate URL
guidance
consolidates tracking-parameter variants onto the canonical page. As long as
your pages declare a rel="canonical" URL — most frameworks and CMSs do this
by default — a tagged URL is treated as the same page as the clean one.
If you are sharing a link you copied from ChatGPT and just want it tidy,
delete ?utm_source=chatgpt.com from the end. If other parameters follow it,
delete utm_source=chatgpt.com& instead and keep the ?. Browser extensions
that do this automatically exist, but you do not need one for an occasional
link.
Does utm_source=chatgpt.com show up in Google Search Console?
Not in any case we could find documented. Search Console reports the URLs Google indexes, and Google crawls your site directly rather than through ChatGPT's links. If a tagged URL did get crawled through a shared link, the canonical tag would consolidate it; at worst it would appear under "Alternate page with proper canonical tag," which needs no action.
Is utm_source=chatgpt.com a virus or a security risk?
No. It is a plain text parameter at the end of a URL, with no code attached. It tells the destination site's analytics where the click came from and nothing else. It does not identify you, and the page you land on is identical with or without it.
Does seeing utm_source=chatgpt.com mean ChatGPT recommended my site?
It means ChatGPT linked to your site in an answer and someone clicked it — usually as a cited source. Getting cited in the first place is a separate problem, and mostly a technical one: ChatGPT can only cite pages its search crawler can read. We cover that in why ChatGPT can't see your site and what makes AI engines cite a source. Whether the resulting traffic is worth chasing is its own question, answered with 2026 conversion data in is AI referral traffic worth having.
One cheap input you control is how many independent pages describe your product consistently, because that is what assistants draw on when they summarise it. A LetsLaunch listing is one of those pages, written to be read by both people and AI crawlers — launching on LetsLaunch is free.