Method in one clause: Similarweb estimates of web visits and mobile app sessions for six assistants, and referrals to the top 43,000 sites with more than 100,000 monthly US visits, July 2023 to July 2026; Graphite sells SEO and AEO services and Similarweb sells the data.
The six assistants reached about 76 billion sessions a month worldwide in September, up 37% year over year, with 89% of sessions on mobile in Q3. AI referrals grew 92% worldwide and 75% in the US year over year (July), but averaged "less than 1%" of website traffic. In Q2 2026, US organic search sent 49 times as many visits as AI referrals, and paid search 8 times as many. July share of AI referrals: ChatGPT 60% worldwide (66% US), Gemini 14% (10% US), Claude 10% (11% US). Claude's sessions grew 1,901%, the largest percentage gain. Perplexity was the only assistant to decline, down 27% in sessions globally. Graphite's March edition had said AI sessions equalled 56% of search worldwide; it now says it "can no longer reliably compare" AI use with search engines, after finding the Android app had been undercounted.