Does Microsoft Copilot Use the Same Index as ChatGPT?

By Cory Maki · Oct 10, 2026

Short answer: largely yes. Microsoft Copilot and ChatGPT's web search both lean on Bing's index to see the live web. They are different products with different models, but when it comes to which pages they can find, they draw from a lot of the same well. Here is the fuller picture, and why it matters for being found in both.

The shared foundation: Bing

Copilot is a Microsoft product built on Bing's search infrastructure — when it looks something up, it is querying Bing's index. ChatGPT, when it browses the web to answer, has also relied on Bing's search results as a core source. So the practical implication is the one most people miss: if you are not in Bing's index, you are invisible to both. Everyone optimizes for Google and forgets that the AI assistants their buyers use are often reading Bing.

This is the same blind spot behind why ChatGPT can't see your website — the fix usually starts with confirming you are actually indexed in Bing, not Google.

Where they differ

They are not identical:

• The model differs. Copilot runs on Microsoft's stack (GPT-family models via its own orchestration); ChatGPT runs OpenAI's models directly. Same index, different reasoning on top.
• ChatGPT has its own crawler. OpenAI operates its own crawlers (OAI-SearchBot and others) and has been building more of its own retrieval, so ChatGPT is not purely dependent on Bing the way Copilot is.
• The surfaces differ. Copilot is woven through Windows, Edge, and Microsoft 365; ChatGPT is its own app and API. Where the answer appears shapes who sees it.

So: heavily overlapping on what they can find, distinct on how they reason and where they show up.

What this means for being cited

Because both lean on Bing, the groundwork is the same:

1. Confirm you are indexed in Bing. Run site:yourdomain.com on Bing. If you are thin there, fix that first — it gates visibility in both.
2. Earn the sources these engines trust. Being indexed gets you findable; being cited comes from authority off your own site — especially Reddit and community sources, which carry weight across AI assistants.
3. Structure content to be quotable — clear answers to specific questions the model can lift.

That is the heart of generative engine optimization: be indexed where the engine reads, and be the citable source it trusts.

Check your coverage

A free AI visibility report shows whether Copilot and ChatGPT surface your brand for your buying questions — and what they cite when they do.