Simon Willison · 2026-08-20 · notable
Simon Willison — ChatGPT search now scopes one query in six to a single site
Simon Willison flags Promptwatch data showing ChatGPT's use of site:-scoped search queries jumped from 0.37% to 16.8% of all fanout queries on 8 August 2026, right after OpenAI updated GPT-5.6 Sol in ChatGPT.
Promptwatch caught ChatGPT switching to domain-scoped search almost overnight, and Simon Willison explains what likely changed.
What is it?
Something changed in how ChatGPT searches the web on 8 August 2026, and Simon Willison's post walks through the evidence. Promptwatch measured the share of ChatGPT fanout queries that use the site: operator: it sat between 0.3% and 0.5% for weeks, dipped to 0.15% from 3 to 5 August, then jumped to 16.8% on 8 August and has stayed at 16-17%.
How does it work?
Fanout queries are the individual searches ChatGPT fires off behind one answer. Willison doubts OpenAI is literally telling the model to type site: in a query, and suggests the search tool signature now looks more like search(query, recency, domains), with the domain filter rendered as a site: clause. He ties the timing to OpenAI's 6 August note that it was updating GPT-5.6 Sol in ChatGPT to be more reliable with facts and give more focused answers. Promptwatch also recorded average fanout queries per response rising from about 1.08 to 1.83 the same day, so scoped searches are being added rather than swapped in.
Why does it matter?
Domain-scoped retrieval decides which sites an AI answer can cite at all, which is the whole game for anyone whose traffic now arrives through a chatbot. A separate Promptwatch report on 18 August found ChatGPT had sharply cut how often Reddit shows up in those searches; Willison notes he cannot confirm whether a system prompt was changed to discourage it.
Who is it for?
publishers, SEO and GEO practitioners, and anyone tracking AI search citations
Try it
https://promptwatch.com/data/chatgpt-site-operator-fanouts