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How ChatGPT search works: Bing, rewritten queries and crawlers

How ChatGPT search works: it has no web index of its own that we can find in any source. OpenAI says a version of GPT-4o tuned for search rewrites your question, sends it to outside search providers including Bing, and writes the answer with citations. Every claim below links to OpenAI's or Microsoft's own documentation.

Published 2026-07-22Updated 2026-10-048 primary4 min read

Michael NefedovFounder

What is ChatGPT search?#

ChatGPT search uses outside search providers, as well as content from partners. The search model is a version of GPT-4o tuned for search.[1] It grew out of the SearchGPT prototype (July 2024) and launched as ChatGPT search on October 31, 2024.[5][1] It cannot cite a page a search provider did not return, and a provider cannot return a page that is not in its index. So the work happens at the search layer, which OpenAI does not own.

How does your question become a search?#

ChatGPT does not search your exact words. It rewrites your question into one or more targeted queries and sends them to its providers. After reading the first results it can send more, narrower queries.[2]This is often called query fan-out: one question becomes several searches. Your page is matched on the rewrite, not on the user's own words. A page that answers one exact version of the question can still be pulled in on the second or third search, even if it loses the broad one.

Does ChatGPT use Bing?#

Yes, for part of it. OpenAI's help center points to the privacy policies of Bing (Microsoft) and Shopify as the search providers ChatGPT sends queries to.[2] Microsoft confirms it: Bing powers a wide range of AI and search experiences, including Yahoo, DuckDuckGo, Microsoft Start, and AI tools like ChatGPT.[4] No source shows OpenAI operating a general web index. The setup can change: Microsoft retired the public Bing Search APIs on August 11, 2025, and moved customers to Grounding with Bing Search in Azure AI Agents.[6] The practical point stands. If Bing has not indexed your page, ChatGPT search has nothing of yours to cite.

What are OpenAI's three crawlers?#

Allow OAI-SearchBot in robots.txt and at your CDN. Treat GPTBot as a separate, deliberate choice.[3]

What does OpenAI not say?#

OpenAI publishes no index size, no retrieval design and no ranking algorithm. Its help center says only that ranking is based on a number of factors meant to surface reliable, relevant information, and that there is no way to guarantee top placement.[2] Anyone selling an exact ChatGPT ranking formula is guessing.

Three checks follow from what is documented: is the page in Bing (use Bing Webmaster Tools), is OAI-SearchBot allowed, and does the page answer the rewritten question in its first lines. Adding statistics, quotes and citations to authoritative sources raised how often a source was surfaced in the founding GEO research.[7] For the full fix list, read why your company isn't in ChatGPT. Other engines differ: across 100,000 identical prompts, ChatGPT and Perplexity shared only 11% of cited sources.[8] See how Perplexity search works.

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Sources

1. ChatGPT search uses outside search providers, running a version of GPT-4o tuned for search: OpenAI, “Introducing ChatGPT search”, October 31, 2024.
2. ChatGPT “rewrites your query… sends those providers” and refines iteratively; names “Bing (Microsoft)” and “Shopify”; ranking is “based on a number of factors” with “no way to guarantee top placement”: OpenAI Help Center, “ChatGPT Search”.
3. “GPTBot is used to crawl content that may be used in training”; “OAI-SearchBot is used to surface websites in search results”; opting out of OAI-SearchBot means a site “will not be shown in ChatGPT search answers”; ChatGPT-User is “not used to determine whether content may appear in Search”: OpenAI, “Overview of OpenAI Crawlers”.
4. “Bing powers a wide range of AI and search experiences, including Yahoo, DuckDuckGo, Microsoft Start, and AI tools like ChatGPT and Inflection.ai”: Microsoft Bing Webmaster Blog, June 17, 2025.
5. SearchGPT prototype, the origin of ChatGPT search: OpenAI, “SearchGPT Prototype”, July 25, 2024.
6. Bing Search APIs “retired on August 11, 2025”; migrate to “Grounding with Bing Search as part of Azure AI Agents”: Microsoft Learn, “Bing Search APIs Retiring on August 11, 2025”, announced May 15, 2025.
7. Statistics, quotations, and citations measurably raise AI visibility: Aggarwal et al., “GEO: Generative Engine Optimization”, arXiv:2311.09735 (KDD 2024).
8. ChatGPT and Perplexity share 11.0% of cited sources across 100,000 prompts: Profound, July 2025.

Every architecture claim quotes OpenAI's or Microsoft's own documentation, blog, or help center, retrieved and verified on July 22, 2026. OpenAI does not disclose its ranking algorithm or index. Study figures are cited as published by their sources.