As AI answer engines became a primary discovery channel, site owners gained a new set of decisions: which AI bots to allow, how to expose content cleanly to language models, and whether to adopt emerging conventions like llms.txt. This guide clarifies what each mechanism actually does. It complements our [AI search optimization guide](/ai-search-optimization-guide/) and the citation tactics in [how to get cited by Perplexity](/perplexity-seo/).

llms.txt A proposed convention, introduced by Jeremy Howard in 2024, for a Markdown file at your site root (/llms.txt) that gives LLMs a curated, human-readable map of your most important content and links to clean Markdown versions of pages.

What llms.txt Is — and What It Is Not

llms.txt is not robots.txt for AI. It does not grant or deny crawler access. It is a helper file that points models toward your best, cleanest content so they can ingest it efficiently at inference or training time. Think of it as a curated table of contents written in Markdown, often paired with an llms-full.txt that concatenates the actual content.

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- [AI Search Optimization Guide](https://ottawaseo.net/ai-search-optimization-guide/): Pillar guide to AI search.
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As of early 2026 no major provider — Google, OpenAI, Anthropic, or Perplexity — has publicly confirmed that it reads llms.txt at scale. Treat it as a low-cost, forward-looking convention, not a ranking or citation guarantee.

The AI Crawlers You Actually Need to Manage

Access is controlled through robots.txt user-agent directives, not llms.txt. Different bots serve different purposes — some train models, some power live search retrieval — and you may want different rules for each. Blocking a training bot but allowing a search bot is a common middle-ground strategy for preserving citation visibility while limiting training use.

User-agentOperatorPrimary Purpose
GPTBotOpenAIModel training
OAI-SearchBotOpenAIChatGPT Search results & citations
Google-ExtendedGoogleGemini training (separate from Googlebot)
PerplexityBotPerplexityIndexing for answer citations
ClaudeBotAnthropicModel training
Applebot-ExtendedAppleApple Intelligence training
Google-Extended and Applebot-Extended control AI training use only. Blocking them does NOT remove you from Google Search or Siri results, because those use the standard Googlebot and Applebot. Keep the standard bots allowed so you stay indexed and eligible for AI Overviews.

A Practical Access Strategy

  1. Decide your goal: maximum AI visibility, or maximum content control. Most publishers seeking traffic choose visibility.
  2. Allow retrieval/search bots (OAI-SearchBot, PerplexityBot, Googlebot) so you remain eligible for citations.
  3. Choose your training-bot stance (GPTBot, Google-Extended, ClaudeBot) based on how you value your content being used in training.
  4. Publish an llms.txt as a curated index for the engines that may adopt it — cheap insurance.
  5. Monitor server logs to verify which AI bots actually visit and how often.
# Allow AI search bots, block training bots (example stance)
User-agent: OAI-SearchBot
Allow: /
User-agent: PerplexityBot
Allow: /

User-agent: GPTBot
Disallow: /
User-agent: Google-Extended
Disallow: /
Canadian context: Canada's privacy and IP frameworks (including proposed AI legislation) remain in flux, and some organizations restrict AI training crawlers for compliance or brand reasons. Document your chosen stance so it can be revisited as policy evolves.
Blocking AI training crawlers
  • Reduces unpaid use of your content for model training.
  • Aligns with stricter data-governance or licensing goals.
  • Blocking search bots too aggressively removes you from AI citations.
  • Enforcement relies on bot cooperation; not all crawlers honor robots.txt.
  • You may forfeit brand-visibility upside in AI answers.

Does llms.txt control which AI can crawl my site?

No. Crawler access is governed by robots.txt user-agent rules. llms.txt is a content-guidance file, not an access-control mechanism.

Will publishing llms.txt help me rank in AI search?

There is no confirmed ranking or citation benefit yet, because major engines have not confirmed they consume it. It is low-cost future-proofing, not a guaranteed lever.

If I block GPTBot, will I disappear from ChatGPT Search?

Not necessarily. GPTBot handles training; OAI-SearchBot handles live search retrieval. Block GPTBot but allow OAI-SearchBot to stay eligible for citations.

  • llms.txt guides models to your best content; it does not control access.
  • Crawler access is still managed through robots.txt user-agent rules.
  • Training bots and search bots are separate — treat them differently.
  • Blocking Google-Extended does not remove you from Google Search.
  • Monitor logs to confirm which AI crawlers actually visit your site.