Short answer: ChatGPT search gets its web results from outside search providers. OpenAI hasn't published the full list, but has said Bing is an important one. Google's results match only a small share of the pages ChatGPT cites. So if you want ChatGPT to find you, check how your pages do on Bing, not only on Google.

What OpenAI has said

When ChatGPT searches the web, it doesn't send your whole question to a search engine. It rewrites the question into one or more shorter searches and sends those to its search providers, sometimes followed by more specific searches after it has read the first results (OpenAI help: ChatGPT search).

When OpenAI launched ChatGPT search, it said it “leverages third-party search providers, as well as content provided directly by our partners” (OpenAI). It didn't name the providers. Asked in a Reddit AMA which search engine it uses, OpenAI's VP of Engineering said they use a set of providers and that “Bing is an important one” (Search Engine Journal).

OpenAI also runs its own crawler for search, OAI-SearchBot. It visits pages so they can be shown in ChatGPT search answers (OpenAI crawlers).

What the studies show

  • Most cited pages come from search results. Ahrefs looked at 1.4 million ChatGPT prompts and found that 88% of the pages ChatGPT cited were taken directly from search results (Ahrefs). Ranking in search is still the way in.
  • Google's results don't explain them. Researchers at the National University of Singapore ran about 4,200 ChatGPT answers and compared the cited pages with what other search tools return. Google alone found under 10% of the exact pages ChatGPT cited. Together with OpenAI's own search tool for developers, it found about a quarter of the pages, and about half of the websites (NUS).

The NUS study didn't test Bing, so it doesn't tell us how much of the rest Bing covers. What it does show is that a good Google ranking is no guarantee you are in the results ChatGPT reads.

What it means for your site

  1. Add your site to Bing Webmaster Tools and submit your sitemap, the same way you would in Google Search Console. You can import your sites from Search Console in a few clicks.
  2. Turn on IndexNow. It tells Bing about new and changed pages right away, instead of waiting for Bing to come back. Many website builders and SEO plugins have it built in.
  3. Search Bing for your customers' questions. If your page is missing there, fix that first: in Bing Webmaster Tools, URL Inspection shows whether Bing has a page and what is stopping it.
  4. Let OAI-SearchBot in. If your robots.txt or your host's bot protection blocks it, ChatGPT can't show your pages in search. The free checker tells you in a few seconds.

Sources