Neither, going by OpenAI's own documentation, and the popular answer is out of date. ChatGPT search runs on an index OpenAI builds itself with a crawler called OAI-SearchBot, supplemented by third-party partners it does not name. We rendered OpenAI's ChatGPT search page on 19 September 2026 and counted: it mentions Bing zero times. Blue Crane Works, in Hamilton, Ontario, rechecks this against the live document rather than repeating it.
Where does ChatGPT get its information?
Three places, and they are worth separating because people collapse them. First, what the model learned during training, which is fixed and has a cutoff date. Second, OpenAI's own search index, built and refreshed by its crawler OAI-SearchBot. Third, what OpenAI's help page calls partners: "to provide relevant responses to your questions, ChatGPT search sometimes partners with other search providers." It does not name them in that sentence.
When you ask something current, it is the second and third that answer you, and the citations you see under the reply come from there.
Didn't ChatGPT used to run on Bing?
Yes, and that is why the claim is everywhere. ChatGPT search launched on Microsoft's infrastructure, the SEO industry learned "ChatGPT runs on Bing", and the sentence outlived the arrangement. It is now repeated in articles, in pitch decks and by other AI assistants, which is how a stale fact becomes self-reinforcing.
So we measured rather than argued. On 19 September 2026 we rendered OpenAI's ChatGPT search help page in a real browser, because the page returns an error to simple fetching tools, and searched the resulting text. The word "Bing" appears zero times. "Google" appears twice, both times about installing a ChatGPT extension in Chrome, which is nothing to do with where results come from. The only search partner whose privacy policy the page links is Shopify's.
We are labelling that as our own measurement of a live page on a stated date, not as an OpenAI announcement. OpenAI has not published a notice saying "we no longer use Bing". What we can say exactly is what its current documentation does and does not contain.
Does that mean Bing does not matter any more?
No, and this is where the correction usually overshoots. Bing matters for reasons that have nothing to do with ChatGPT:
| Reason | What it gets you |
|---|---|
| Copilot grounds on Bing | Microsoft's assistant, in Windows and Office, cannot cite a site Bing has not indexed. |
| Bing's guidelines are the most specific | It names client-side rendering as a thing to avoid, with grounding consequences. Google only recommends against it. |
| IndexNow is instant | A new page reaches Bing in minutes instead of waiting to be crawled, and the ping reaches several engines at once. |
| It is a real index with real users | Ordinary search traffic, free to claim, and the only free query data besides Google's. |
What changed is the reasoning, not the recommendation. Do Bing because those four things are true, not because somebody told you it is the back door into ChatGPT.
What actually decides whether ChatGPT can use your site?
OpenAI answers this in one sentence, and it names your own server and your own CDN, not a search engine:
"To make a website eligible for inclusion, allow OAI-Searchbot to crawl the site and confirm that the website host or content delivery network allows traffic from OpenAI's published searchbot IP addresses."
OpenAI, Searching the web with ChatGPT, read 19 September 2026
That is the whole documented gate. Two settings, both on infrastructure you control. If you were going to act on one thing from this page, it is that sentence rather than anything about Bing.
How can I check this myself?
You should, because this is exactly the kind of fact that goes stale. The help page blocks simple fetching tools, so open it in an ordinary browser, use your browser's find-on-page, and search for "Bing". Then do the same on OpenAI's crawler documentation, which is the page that tells you which crawler controls what.
If OpenAI names an upstream index again, that find-on-page will show it in seconds, and this article will be wrong. We would rather tell you how to check than ask you to trust us.
What this means for a local business
Stop thinking of it as getting into somebody's directory and start thinking of it as being readable. The practical list is short and we wrote it out in how do I add my business to ChatGPT, and the diagnosis for a site that is already failing is in why isn't my business showing up in ChatGPT. Or run the free check and have it measured.
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