{"name":"AI assistant referrers","version":"1.0.0","last_verified":"2026-10-19","license":"CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)","attribution":"AnswerTraffic (https://answertraffic.com/referrers)","count":16,"referrers":[{"utm_source_value":"chatgpt.com","evidence_url":"https://ahrefs.com/blog/generative-engines-are-breaking-web-analytics/","evidence_date":"2025-05","first_seen":"2025-06-13","last_verified":"2026-10-19","ga4_default":"named","plausible":"named","matomo":"named","posthog":"named","ambiguous":false,"assistant_id":"chatgpt","assistant":"ChatGPT","operator":"OpenAI","hostname":"chatgpt.com","surface":"Web","referrer_behavior":"partial","evidence_type":"third_party_test","note":"Ahrefs test (May 2025): links from free accounts sent a referrer, inline links on paid accounts used noreferrer; source links carried ?utm_source=chatgpt.com. First reports of the parameter on more links: 13 June 2025. The mobile app was reported to send no referrer. Behaviour changed in October 2026 (see incidents)."},{"utm_source_value":null,"evidence_url":null,"evidence_date":null,"first_seen":null,"last_verified":"2026-10-19","ga4_default":"named","plausible":"named","matomo":"named","posthog":"named","ambiguous":false,"assistant_id":"chatgpt","assistant":"ChatGPT","operator":"OpenAI","hostname":"chat.openai.com","surface":"Web (older hostname)","referrer_behavior":"unknown","evidence_type":"unverified","note":"Listed in third-party filters; we have no test or vendor document for this hostname yet. ChatGPT used this hostname before chatgpt.com; the assistant itself is named by the tools, the hostname is not."},{"utm_source_value":null,"evidence_url":"https://ahrefs.com/blog/generative-engines-are-breaking-web-analytics/","evidence_date":"2025-05","first_seen":null,"last_verified":"2026-10-19","ga4_default":"not_named","plausible":"named","matomo":"named","posthog":"named","ambiguous":false,"assistant_id":"perplexity","assistant":"Perplexity","operator":"Perplexity AI","hostname":"perplexity.ai","surface":"Web","referrer_behavior":"sent","evidence_type":"third_party_test","note":"Ahrefs test (May 2025): web version sent a referrer; the desktop app sent none; mobile was not tested."},{"utm_source_value":null,"evidence_url":null,"evidence_date":null,"first_seen":null,"last_verified":"2026-10-19","ga4_default":"not_named","plausible":"named","matomo":"named","posthog":"named","ambiguous":false,"assistant_id":"perplexity","assistant":"Perplexity","operator":"Perplexity AI","hostname":"www.perplexity.ai","surface":"Web (www variant)","referrer_behavior":"unknown","evidence_type":"unverified","note":"Listed in third-party filters; we have no test or vendor document for this hostname yet."},{"utm_source_value":null,"evidence_url":"https://ahrefs.com/blog/generative-engines-are-breaking-web-analytics/","evidence_date":"2025-05","first_seen":null,"last_verified":"2026-10-19","ga4_default":"one_source","plausible":"named","matomo":"named","posthog":"named","ambiguous":false,"assistant_id":"claude","assistant":"Claude","operator":"Anthropic","hostname":"claude.ai","surface":"Web","referrer_behavior":"sent","evidence_type":"third_party_test","note":"Ahrefs test (May 2025): every tested link sent a referrer. GA4's release note names Claude; SEJ reports that GA4's later documentation does not."},{"utm_source_value":null,"evidence_url":"https://ahrefs.com/blog/generative-engines-are-breaking-web-analytics/","evidence_date":"2025-05","first_seen":null,"last_verified":"2026-10-19","ga4_default":"named","plausible":"named","matomo":"named","posthog":"unknown","ambiguous":false,"assistant_id":"gemini","assistant":"Gemini","operator":"Google","hostname":"gemini.google.com","surface":"Web","referrer_behavior":"partial","evidence_type":"third_party_test","note":"Ahrefs test (May 2025): usually sent a referrer; Deep Research (\"researching websites\") used noreferrer."},{"utm_source_value":null,"evidence_url":"https://patrickstox.com/ai-search/measurement-and-reporting/ai-traffic-attribution/","evidence_date":"2025-05","first_seen":null,"last_verified":"2026-10-19","ga4_default":"one_source","plausible":"named","matomo":"named","posthog":"unknown","ambiguous":false,"assistant_id":"copilot","assistant":"Microsoft Copilot","operator":"Microsoft","hostname":"copilot.microsoft.com","surface":"Web","referrer_behavior":"partial","evidence_type":"third_party_test","note":"Reported to switch between sending and not sending a referrer over the months; the Windows app sent none. Table form after the Ahrefs test (May 2025)."},{"utm_source_value":null,"evidence_url":null,"evidence_date":null,"first_seen":null,"last_verified":"2026-10-19","ga4_default":"one_source","plausible":"named","matomo":"named","posthog":"unknown","ambiguous":false,"assistant_id":"copilot","assistant":"Microsoft Copilot","operator":"Microsoft","hostname":"edgeservices.bing.com","surface":"Edge sidebar / Bing (reported)","referrer_behavior":"unknown","evidence_type":"unverified","note":"Seen in third-party regex lists (weak evidence); not tested by us."},{"utm_source_value":null,"evidence_url":"https://patrickstox.com/ai-search/measurement-and-reporting/ai-traffic-attribution/","evidence_date":"2025-05","first_seen":null,"last_verified":"2026-10-19","ga4_default":"one_source","plausible":"unknown","matomo":"unknown","posthog":"unknown","ambiguous":false,"assistant_id":"grok","assistant":"Grok","operator":"xAI","hostname":"grok.x.com","surface":"Grok on X","referrer_behavior":"partial","evidence_type":"third_party_test","note":"Reported: the standalone Grok app sends no referrer, Grok inside X does. Hostname after a third-party table (May 2025)."},{"utm_source_value":null,"evidence_url":null,"evidence_date":null,"first_seen":null,"last_verified":"2026-10-19","ga4_default":"one_source","plausible":"unknown","matomo":"unknown","posthog":"unknown","ambiguous":false,"assistant_id":"grok","assistant":"Grok","operator":"xAI","hostname":"grok.com","surface":"Web","referrer_behavior":"unknown","evidence_type":"unverified","note":"Listed in third-party filters; we have no test or vendor document for this hostname yet."},{"utm_source_value":null,"evidence_url":"https://patrickstox.com/ai-search/measurement-and-reporting/ai-traffic-attribution/","evidence_date":"2025-05","first_seen":null,"last_verified":"2026-10-19","ga4_default":"one_source","plausible":"unknown","matomo":"unknown","posthog":"unknown","ambiguous":false,"assistant_id":"deepseek","assistant":"DeepSeek","operator":"DeepSeek","hostname":"chat.deepseek.com","surface":"Web","referrer_behavior":"partial","evidence_type":"third_party_test","note":"Reported: no referrer except for links in web-search citations. The source table does not name the hostname, so the hostname itself is unverified."},{"utm_source_value":null,"evidence_url":"https://ahrefs.com/blog/generative-engines-are-breaking-web-analytics/","evidence_date":"2025-05","first_seen":null,"last_verified":"2026-10-19","ga4_default":"unknown","plausible":"unknown","matomo":"named","posthog":"unknown","ambiguous":false,"assistant_id":"meta-ai","assistant":"Meta AI","operator":"Meta","hostname":"www.meta.ai","surface":"Web","referrer_behavior":"sent","evidence_type":"third_party_test","note":"Ahrefs test (May 2025): referrer sent."},{"utm_source_value":null,"evidence_url":"https://ahrefs.com/blog/generative-engines-are-breaking-web-analytics/","evidence_date":"2025-05","first_seen":null,"last_verified":"2026-10-19","ga4_default":"unknown","plausible":"unknown","matomo":"named","posthog":"unknown","ambiguous":false,"assistant_id":"mistral","assistant":"Le Chat (Mistral)","operator":"Mistral AI","hostname":"chat.mistral.ai","surface":"Web","referrer_behavior":"sent","evidence_type":"third_party_test","note":"Ahrefs test (May 2025): referrer sent."},{"utm_source_value":null,"evidence_url":null,"evidence_date":null,"first_seen":null,"last_verified":"2026-10-19","ga4_default":"unknown","plausible":"unknown","matomo":"unknown","posthog":"unknown","ambiguous":false,"assistant_id":"you","assistant":"You.com","operator":"You.com","hostname":"you.com","surface":"Web","referrer_behavior":"unknown","evidence_type":"unverified","note":"Listed in third-party filters; we have no test or vendor document for this hostname yet."},{"utm_source_value":null,"evidence_url":null,"evidence_date":null,"first_seen":null,"last_verified":"2026-10-19","ga4_default":"unknown","plausible":"unknown","matomo":"named","posthog":"unknown","ambiguous":false,"assistant_id":"iask","assistant":"iAsk","operator":"iAsk","hostname":"iask.ai","surface":"Web","referrer_behavior":"unknown","evidence_type":"unverified","note":"Matomo names iAsk as a known assistant; the hostname and its referrer behaviour are unverified."},{"utm_source_value":null,"evidence_url":"https://patrickstox.com/ai-search/measurement-and-reporting/ai-traffic-attribution/","evidence_date":"2025-05","first_seen":null,"last_verified":"2026-10-19","ga4_default":"unknown","plausible":"unknown","matomo":"unknown","posthog":"unknown","ambiguous":true,"assistant_id":"google-ai","assistant":"Google AI Overviews / AI Mode","operator":"Google","hostname":"google.com","surface":"Search","referrer_behavior":"sent","evidence_type":"third_party_test","note":"Not distinguishable: AI Overviews and AI Mode clicks are counted as google / organic, the same as classic results. Google's documentation counts them under Web in Search Console. Excluded from generated filters."}],"source":"https://answertraffic.com/referrers"}