AI referrers
Which AI tools send you real visitors, and how we tell.
When a person clicks a link inside an AI tool and lands on your site, their browser passes along a referrer, the address of the page they came from. A visit that arrives with a referrer of chatgpt.com, claude.ai, or perplexity.ai is a person who clicked through from that tool. Reading and classifying that referrer is how Visibility Kit, and Google Analytics, tell AI traffic apart from everything else.
Tools we identify
Each tool sends traffic from one or more domains. A visit from any of them is logged as coming from that tool.
| Tool | Referrer domains |
|---|---|
| ChatGPT | chatgpt.com, chat.openai.com, openai.com |
| Claude | claude.ai |
| Gemini | gemini.google.com, bard.google.com |
| Perplexity | perplexity.ai |
| Copilot | copilot.microsoft.com |
| Meta AI | meta.ai |
| DeepSeek | deepseek.com |
| Grok | grok.com, grok.x.ai |
| You.com | you.com |
| Brave | search.brave.com |
| Kagi | kagi.com |
This is the same list to match against if you are pulling the data out of Google Analytics yourself. See Getting clean AI traffic out of Google Analytics.
Where the referrer holds up, and where it doesn't
Most of the time the referrer is reliable. The tool sends the visitor with its domain attached, and the visit gets attributed correctly. There are two cases where it falls short, and both are worth knowing so you read the numbers fairly.
Some tools strip the referrer on the way out, usually for privacy. When that happens the browser arrives with nothing attached, and there is no way to tell the visit came from an AI tool. Analytics files it under Direct, in with bookmarks and typed-in addresses. The visit is real, but it is invisible as AI traffic, and nothing on the receiving end can recover a source the browser chose not to send.
The other case is link tagging. A few tools add a tag to the links in their answers, something like utm_source=chatgpt.com, which survives even when the referrer is stripped. When a tool does this, the visit is easy to attribute. Most tools do not do it consistently, so the plain referrer is still the signal we lean on. The practical effect is that your real AI traffic is at least what you see, and probably a little more, with the gap sitting unattributed in Direct.
What gets logged
Each referral session records the tool that sent the visit, the landing page, basic browser and device context, a timestamp, and an anonymized visitor id that keeps later pageviews tied to the same session.
What doesn't get logged
We do not record the question the person asked the AI, because the tools do not pass the prompt along in the referrer. We do not see which specific answer cited you, for the same reason. And we do not record personally identifiable information about the visitor.
Session continuity
When an AI-referred visitor moves to other pages on your site, those pageviews stay attributed to the same AI-sourced session, the way analytics keeps an organic search session together. The referrer that started the session carries through for as long as the session stays active.