AI referral traffic

A referral is attributed when the browser sends a Referer header naming an AI host. Cloudflare divides HTML requests from a platform's crawlers by HTML requests carrying that platform's Referer to give a crawl-to-refer ratio^[4]. The method has a known blind spot: native desktop and mobile apps send no Referer header, so app-driven visits are invisible and published ratios read worse than reality^[5].

Cloudflare put the July 2025 figure at 38,065.7 crawls per referral for Anthropic, 1,091.4 for OpenAI, 194.8 for Perplexity, 40.7 for Microsoft, 5.4 for Google and 0.9 for ByteDance^[3]. The spread moves quickly. Anthropic's ratio fell 86.7% across the first seven months of 2025 while Perplexity's rose 256.7%^[6]. Expressed as effort per visit, Cloudflare chief executive Matthew Prince reckoned traffic 750 times harder to win through OpenAI and 30,000 times harder through Anthropic than through what he calls the Google of old^[7].

Adobe Analytics measured generative AI referrals to US retail sites up 1,200% in February 2025 against July 2024, about a doubling every two months^[8]. Growth in the referring platforms themselves continued: 9.5 billion average monthly visits across generative AI platforms between June 2025 and May 2026, up 70% year on year^[9]. The shape of the referral also changed, with ChatGPT homepage links rising from about 27% of its outbound referrals to roughly 62% by late May 2026^[10], which sends visitors to a domain rather than to the page that answered the question.

AI-referred visitors to US retail sites stayed 8% longer, viewed 12% more pages and bounced 23% less than other traffic^[11]. They converted less often, 9% below other sources in February 2025 against 43% below in July 2024^[12]. A vendor study of digital marketing topics reached the opposite conclusion, valuing an AI search visit at 4.4 times an organic one on conversion rate^[13]; the two disagree because they measure different verticals and different definitions of value, and the second is an extrapolation rather than a direct measurement. Neither total captures answers a user never clicks, which is the subject of zero-click search and the reason a brand mention is counted alongside sessions.