Which Search Index Does Each AI Engine Use? ChatGPT, Gemini, Perplexity, Claude, Copilot (2026)

The short answer

ChatGPT and Microsoft Copilot read the Bing index. Google AI Overviews and Gemini read the Google index. Perplexity runs its own index. Claude reads the Brave Search index. That is four separate index memberships, not one. A business indexed in Google is eligible for Gemini and AI Overviews — and can still be structurally invisible to ChatGPT, because ChatGPT does not read Google.

Which search index each AI engine uses to choose citations — Get AI Cited (getaicited.ai), Dubai.

The table

AI engine	Search index it reads	What that means for you
ChatGPT	Bing	Your Google rank is irrelevant here. Verify in Bing Webmaster Tools.
Microsoft Copilot	Bing	Same index as ChatGPT. Bing also reports your Copilot citations for free.
Google AI Overviews	Google	Classic SEO transfers here. Google Business Profile does real work.
Gemini	Google	Grounded in Google Search. Allow `Google-Extended`.
Perplexity	Its own	Own crawler, own index, recency-weighted. Allow `PerplexityBot`.
Claude	Brave Search	Almost nobody optimises for this. Least contested engine.

Compiled July 2026 from public reporting and vendor documentation. Engine architectures change; we date this page and revise it rather than presenting it as permanent.

Why this is the most useful table in AI visibility

Almost every guide to “getting cited by AI” treats the engines as one thing. They are not. They do not share an index. A business can be:

Indexed in Google — and therefore eligible for Gemini and AI Overviews;
Absent from Bing — and therefore structurally invisible to ChatGPT and Copilot, no matter what it does on-page;
Never crawled by PerplexityBot — and therefore absent from Perplexity entirely;
Missing from Brave — and therefore uncitable by Claude.

That is four separate index memberships, not one. Optimising for Google and assuming the rest follows is the single most common and most expensive mistake in this category.

The reported evidence

ChatGPT → Bing. Analysis by Seer Interactive reported that roughly 87% of ChatGPT citations matched Bing’s top results. ChatGPT Search retrieves from the Bing index.
Copilot → Bing. Copilot generates a short query from the prompt and sends it to Bing.
Gemini and AI Overviews → Google. Both are grounded in Google Search.
Perplexity → its own index, built by its own crawler. It is the most retrieval-driven and the most recency-weighted of the major engines.
Claude → Brave Search. Claude’s web search is reported to be powered by the Brave index.

We link the reasoning rather than the certainty: these are reported architectures, not published specifications, and the vendors change them. Treat the table as current and dated, not as a law.

What to do with this

Audit all four index memberships, not one. Google Search Console, Bing Webmaster Tools, a PerplexityBot check, and Brave.
Fix the index you are missing before you touch anything on-page. Index membership is a gate, not a ranking factor. Below the gate, on-page work returns nothing.
Allow every AI crawler in robots.txt: GPTBot, OAI-SearchBot, ChatGPT-User, PerplexityBot, Perplexity-User, Google-Extended, ClaudeBot, Claude-Web, Bingbot.
Measure per engine, not in aggregate. “AI visibility” as a single number hides the fact that you may be strong in one index and absent from three.

Get AI Cited (getaicited.ai) is a Dubai-licensed AI-visibility service (Get AI Cited Technology, DET licence 1635658). We do not guarantee rankings or citations — AI answers are controlled by the engines and change day to day. What we commit to is a published method, multi-run measurement and dated logs.

Frequently asked

Which search index does ChatGPT use?

ChatGPT Search retrieves from the Bing index. Analysis by Seer Interactive reported roughly 87% of ChatGPT citations matched Bing's top results. It does not read Google's index.

Which search index does Claude use?

Claude's web search is reported to be powered by the Brave Search index — not Google and not Bing.

Which search index does Perplexity use?

Perplexity primarily uses its own native index, built by its own crawler (PerplexityBot). It is the most retrieval-driven and most recency-weighted of the major engines.

Do Gemini and Google AI Overviews use the Google index?

Yes. Both are grounded in Google Search, which is why classic SEO work transfers to this engine family more directly than to ChatGPT, Perplexity or Claude.

If I rank on Google, will ChatGPT cite me?

Not necessarily, and often not. ChatGPT reads Bing, not Google. If Bing has not indexed your pages, ChatGPT cannot cite you regardless of your Google ranking.

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