Definition
llms.txt is a proposed Markdown file at the root of a website that lists the pages an AI tool should read first. Jeremy Howard proposed it on 3 September 2024. It remains a proposal, and Google says Search ignores the file.
Example. A site serves example.com/llms.txt starting with # Example, a one-line summary, then sections of links to its most useful pages.
The file that does control AI crawlers is robots.txt. Check which bots yours lets in with the free AI Crawler Access Checker.
What goes in an llms.txt file?
An llms.txt file holds a site name as a heading, a short summary, then lists of links. Only the heading is required. A section called Optional holds links an AI tool can skip when it is short on space. The proposal also suggests a plain Markdown copy of important pages at the same address with .md on the end.
Does Google use llms.txt?
Google does not use llms.txt. Its AI optimisation guide says creating one "will neither harm nor help your site's visibility or rankings in Google Search, as Google Search ignores them." It adds that keeping one for other systems is "completely fine".
Do ChatGPT, Claude and Perplexity read llms.txt?
ChatGPT, Claude and Perplexity have not said they use a site's llms.txt to choose what to cite. Their crawler documentation tells site owners to control their bots with robots.txt. OpenAI and Perplexity do publish llms.txt files for their own developer docs.
Is llms.txt worth making?
llms.txt is worth making only if it takes minutes. Across 300+ StudioHawk client sites, sites with one got the same AI assistant visits as sites without: a median of 125.8 against 124.8 per 1,000 non-brand Google clicks (1 October 2025 to 30 September 2026). The full data is in our guide, Are llms.txt and llm-info Pages Worth It?
What is llms-full.txt?
llms-full.txt is a companion file holding the full text of a site's key pages in one Markdown file. It grew up around the proposal. The proposal's core format leaves it out.
Mentioned in
Sources
- Jeremy Howard: The /llms.txt file (llmstxt.org, 3 September 2024)
- Google Search Central: Guide to optimizing for generative AI features on Google Search (updated 10 July 2026)
- OpenAI: Overview of OpenAI crawlers
- Perplexity: Perplexity crawlers
Last checked against these sources on 2 November 2026.