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AI platforms: how ChatGPT, Perplexity, Gemini and the rest find you

The crawler fleet behind every AI answer: which bots fetch your pages, what robots.txt actually controls, and where the evidence says to focus. With primary-source links throughout.

CB
ChatBakers Team
October 2026 · 12 min read

Every AI answer is fetched by a specific bot, under specific rules — and the rules differ per platform. ChatGPT, Perplexity, Gemini, Copilot and Grok each run their own crawlers with their own robots.txt behavior, and peer-reviewed measurements show their citation overlap is small (ChatGPT vs Google: ~12%). One GEO tactic rarely wins everywhere: allow the right crawlers, publish extractable pages, and measure per platform.

Why per-platform work beats generic checklists

A Princeton study (KDD 2024, 10,000 queries) found content edits lift AI visibility by up to 40% — but explicitly concluded optimizations must be domain-specific, not universal checklists. The same applies across platforms: a journal audit of five chatbots found Perplexity and DeepSeek cite many sources while Copilot cites few, and health-science questions pull scholarly sources where legal questions pull blogs. Your buyers don't ask "an AI" — they ask one specific assistant with its own retrieval habits.

The crawler fleet: who fetches your pages

OpenAI (ChatGPT): four bots, independent settings

  • GPTBot — crawls for model training. Block it and you stay out of future training data, but it doesn't affect today's answers.
  • OAI-SearchBot — feeds ChatGPT's live search and citations. This is the one that matters for being quoted.
  • ChatGPT-User — fetches a page when a user explicitly asks about it. It can ignore robots.txt, because the user, not OpenAI, initiated the fetch.
  • OAI-AdsBot — advertising only, irrelevant for citations.

Each bot has independent robots.txt settings with roughly 24-hour propagation, and OpenAI publishes the crawler IP ranges (official bot docs). Practical takeaway: disallow GPTBot if you object to training use, but keep OAI-SearchBot allowed — blocking everything costs you citations for no ranking benefit.

Perplexity: citations are the product

Perplexity splits into PerplexityBot (search index building, explicitly not foundation-model training) and Perplexity-User (on-demand fetch that ignores robots.txt by design). Two consequences practitioners miss: first, a blocked page can still appear — indexed as domain plus headline plus factual summary; second, every claim links a source, so fresh, quotable pages with clear facts win fastest here (crawler docs, robots.txt policy).

Controversy, stated fairly In August 2025 Cloudflare published evidence of Perplexity fetching pages through undeclared crawlers past explicit robots.txt disallows. Perplexity disputed the framing. For your planning the lesson is narrower than the headlines: robots.txt is a request, not a lock — assume motivated fetchers can still read public pages.

Anthropic (Claude): the granular trio

ClaudeBot (training/index), Claude-User (user-triggered) and Claude-SearchBot (search grounding) each honor robots.txt separately, including Crawl-delay (official docs). If Claude answers matter to your buyers, allow Claude-SearchBot while deciding on ClaudeBot for training on its own merits.

Google: the most misunderstood setup

Google-Extended is not a crawler. It is a robots.txt token controlling Gemini training and grounding use — it affects neither rankings nor AI Overviews inclusion, which follow Googlebot. Consequence most guides get wrong: there is no "opt out of AI Overviews but stay in search" switch. The only exits are nosnippet or noindex, both of which also remove you from regular results. Price that trade explicitly before touching anything.

Microsoft (Copilot): the exception

Microsoft runs no separate AI crawler; Copilot grounds through Bing's index. Control is via meta tags (noarchive, nocache, noai) rather than a bot name, and Bing Webmaster Tools reports AI-driven performance. In practice: if Bing indexes you, Copilot can ground on you.

What the evidence says actually moves citations

  • Freshness wins. AI-cited content is about 25.7% fresher than average Google results across 17M citations on 7 platforms — keep money pages updated, not just published.
  • Third-party brand mentions correlate most. Branded web mentions are the top-correlated signal with AI Overview inclusion in Ahrefs/Profound data. Two or three independent comparisons outweigh ten self-published pages.
  • Blocking has a measured price. Publishers blocking AI crawlers lost 23.1% of total traffic (Rutgers/Wharton, December 2025) without consistently denying competitors citations — blocking is a business decision with a number attached, not free insurance.
  • Structure helps extraction, not magic. The Princeton ranking is clear: expert quotes (+41%), statistics (+33%), fluent readable text (+29%), cited sources (+28%) — and keyword stuffing is the only method that hurts (−8 to −10%). An Ahrefs experiment on 1,885 pages found JSON-LD schema alone moves AI citations ~not at all: treat schema as entity hygiene, not a lever.

First steps, in order

  1. Audit robots.txt today. Allow OAI-SearchBot, PerplexityBot, Claude-SearchBot and Googlebot; decide on training bots (GPTBot, ClaudeBot, Google-Extended) separately. One file, ten minutes.
  2. Publish one category-definition page. Plain language, the answer in the first three sentences, 3–5 FAQs. This is the page most likely to be quoted verbatim.
  3. Earn two independent mentions. A niche "best of" list, a review profile, a comparison — anything not on your domain.
  4. Measure per platform. Same 20–30 buyer prompts checked monthly in ChatGPT and Perplexity first; add Gemini and Overviews once those move. Track share of voice, not rank.

Do it in ChatBakers

  1. One prompt set, every platform. Track identical buyer prompts across ChatGPT, Perplexity, Gemini and more — no separate setups.
  2. Per-model citations. Open any prompt to see exactly which sources each assistant quoted, side by side.
  3. Compare and act. Leading in Perplexity but absent in ChatGPT? The dashboard split shows it; the fix list differs per platform (see above).

Guides in this pillar

Related reading

Frequently asked questions

Which AI platform should I optimize for first?

Start where your buyers research. For most B2B, that is ChatGPT first, Perplexity second — Perplexity cites sources explicitly, so wins there are visible fastest. Add Gemini and AI Overviews once the first two move.

Do all models use the same data?

No. Each model mixes training data with its own live web retrieval, and each weights sources differently. ChatGPT citations overlap with Google results by only about 12% (peer-reviewed measurement), so a brand can lead in Perplexity and be absent in ChatGPT. Track per platform, never blended only.

If I block AI crawlers in robots.txt, am I safe?

Not exactly. Some crawlers honor robots.txt (GPTBot, ClaudeBot), but user-triggered fetchers such as ChatGPT-User and Perplexity-User may ignore it by design, and a 2025 Cloudflare investigation documented Perplexity fetching pages that explicitly disallowed it. Blocking also has a measured cost: publishers that blocked AI crawlers lost 23.1% of total traffic in a Rutgers/Wharton study.

Does llms.txt get me cited more?

There is no validated evidence for that. A 300,000-domain SE Ranking analysis found llms.txt changes nothing about how AI systems see or cite content. Treat it as crawler hygiene — a clean machine-readable summary of your site — not as a citation lever.

How do I opt out of Google AI Overviews but stay in search?

There is no AI-Overviews-only opt-out. Google-Extended only controls Gemini training and grounding, not Overviews inclusion (that follows Googlebot). The only way out of Overviews is nosnippet or noindex — which also removes you from regular search results.

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