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Guide · primary sources

Does llms.txt work?

Not for Google, and there's no evidence it helps elsewhere. Google's own Search documentation, updated July 2026, says Google Search doesn't use llms.txt or similar AI text files, including for AI Overviews and AI Mode. OpenAI and Perplexity document the crawlers they do use and don't mention it. It does no harm, so add one if a tool you care about asks for it, but don't expect it to change your AI visibility.

By the AIVisibilityNerd desk · Published undefined undefined, NaN

llms.txt is a proposed plain-text file at the root of a site (like robots.txt) that lists the pages a language model should read. A lot of AI visibility advice says to add one. Here's what the companies whose assistants you want to show up in actually say.

Google: Search doesn't use it

  • Google's Search Central guide on optimizing for its generative AI features (page last updated July 10, 2026) says you don't need llms.txt or other AI-specific text or Markdown files to appear in Google Search or its AI features, because Search itself doesn't use them. It adds that creating them for other services neither helps nor hurts you on Google.
  • Its older AI features page (updated December 2025) says the same thing more generally: no special machine-readable files, AI text files or markup are needed for AI Overviews or AI Mode.
  • Google's John Mueller wrote in April 2025, in a Reddit thread on r/TechSEO, that no AI service had said it uses llms.txt, that server logs show they don't even request it, and that it's comparable to the old keywords meta tag.

One wrinkle: Chrome's Lighthouse tool has an optional "agentic browsing" check that looks for an llms.txt file. That's a Chrome developer audit, not Google Search ranking.

OpenAI and Perplexity: they document crawlers, not llms.txt

  • OpenAI says that to appear in ChatGPT search results, a site should allow its OAI-SearchBot crawler. Its help pages describe ranking by "multiple factors" with no guaranteed placement, and say nothing about llms.txt.
  • Perplexity documents PerplexityBot (for its search results) and a separate fetcher that loads pages when a user asks about them. Again, no mention of llms.txt.

So what actually matters?

Going by what these companies publish: let their search crawlers in (check your robots.txt and any firewall rules for OAI-SearchBot and PerplexityBot), and rank in ordinary search, since ChatGPT says it sends rewritten queries to search providers. Several free tools check crawler access for you; see our free AI visibility checker comparison, which flags the ones that test site readiness rather than mentions.

If a tool you pay for scores you down for "missing llms.txt", that's the tool's opinion, not Google's. Compare what each tracker measures in our price index.

Sources (all read Oct 8, 2026)

  1. Google Search Central, "Optimizing your website for generative AI features on Google Search", last updated 2026-07-10: developers.google.com/search/docs/fundamentals/ai-optimization-guide
  2. Google Search Central, "AI features and your website", last updated 2025-12-10: developers.google.com/search/docs/appearance/ai-features
  3. John Mueller, comment in r/TechSEO thread "LLM.txt – where are we at?", Apr 16, 2025 (retrieved via the Arctic Shift Reddit archive)
  4. Chrome for Developers, Lighthouse "llms.txt" agentic browsing audit: developer.chrome.com/docs/lighthouse
  5. OpenAI Help Center, "Searching the web with ChatGPT" and "Publishers and Developers FAQ"; OpenAI, "Overview of OpenAI Crawlers"
  6. Perplexity docs, "Perplexity Crawlers": docs.perplexity.ai