A year ago, AI search was basically one product with one name: ChatGPT. A new report says that era is already over.

Similarweb’s 2026 Generative AI Landscape report tracks a market that is booming and splintering at once. Generative AI websites drew 9.5 billion visits a month worldwide between June 2025 and May 2026, up 70% on the year. App downloads reached 4.4 billion, up 58%.

The growth is not the surprise. The fragmentation is.

ChatGPT is still the biggest. Its lead is shrinking.

ChatGPT is still the largest standalone AI website, and it remains enormous. But Similarweb says its share of web visits has fallen steadily as Gemini, Claude, Perplexity and DeepSeek pull in audiences of their own.

The app data shows who is climbing. By US monthly active users, year on year, Meta AI grew 435% and Claude 349%. Grok rose 117%, Perplexity 94% and ChatGPT itself 87%. Gemini added 31%. Two names slid backwards: Microsoft’s 365 Copilot fell 31% and DeepSeek 23%.

Google’s answer: bury AI inside search

Google is not standing still. Its AI Overviews now surface on a growing share of US searches, and visits to its conversational AI Mode keep rising. Similarweb puts Overviews on nearly four in ten US searches, pulling more of the journey into an AI-native experience.

That squeezes the open web. News was the only major web category to shrink over the year, down 5%, even as AI chatbots grew 57%. Yet people are not leaving Google: 95% of ChatGPT users still use it too.

AI search is growing up, and some are opting out

The audience is ageing into the mainstream. In May 2024, under-35s were 61% of gen-AI users. By May 2026 they were 50%, with the growth shifting to the over-45s. Durable adoption, the report argues, looks like your parents signing up.

Not everyone is joining. A young cohort is actively opting out and turning to AI-free tools. On DuckDuckGo’s no-AI search, 18-to-24-year-olds make up 33% of users, against 16% of the web overall.

Now come the ads

The clearest sign of a maturing market is that it is filling with ads. In the US, the share of ChatGPT chats carrying an ad jumped from 14% in May 2026 to 26% a month later. Two-thirds appear only after the second prompt, and 65% of users keep chatting once one shows up.

The click-through rate is a slim 0.50%, and the early advertisers are unglamorous: Resume.io, Monday.com and Framer topped the June list. The direction, though, is set.

What it means for brands

For marketers, the report reads as a warning to move. AI referral traffic is surging, up 312% for marketplaces, 278% for news and 237% for travel year on year. The share of ChatGPT answers citing a web source has risen more than fivefold in a year, to 6.8%.

Being the name an AI recommends matters, too. Users visited an AI-recommended brand two to four times as often as a rival. But optimising for AI search is its own game: most referrals, 58.8%, land on homepages, while the pages ChatGPT cites sit two or three folders deep.

“Discovery is no longer tied to a single destination,” said Similarweb’s Baruch Toledano. One caveat runs through the data: these are Similarweb’s estimates from web and app traffic, and they exclude API use and AI folded into other apps. The trend is hard to miss anyway.

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