llms.txt and llms-full.txt
llms.txt and llms-full.txt
llms.txt and llms-full.txt
llms.txt is a standard for exposing website content to AI developer tools. Fern implements this standard, automatically generating and maintaining llms.txt and llms-full.txt Markdown files so AI tools can discover and index your documentation. For single pages, agents can also fetch Markdown directly.
llms.txt and llms-full.txt are root-level files Fern serves to non-human consumers, alongside robots.txt. robots.txt decides which crawlers reach your site and what AI training signals you broadcast; llms.txt and llms-full.txt shape what AI agents receive once they do.
Fern generates two files for LLMs:
llms.txt contains a lightweight summary of your documentation site with each page distilled into a one-sentence description and URL. For sites with API endpoints, it also links to your OpenAPI specification as a standalone, machine-readable file so AI tools can parse your full API schema directly. For sites with WebSocket channels, it also links to your AsyncAPI specification.
llms-full.txt contains complete documentation content including the full text of all pages. For API documentation, this includes your complete API Reference with resolved OpenAPI specifications and SDK code examples for enabled languages.
Both files are available at any level of your documentation hierarchy (/llms.txt, /llms-full.txt, /docs/llms.txt, /docs/ai-features/llms-full.txt, etc.).
Examples: Eleven Labs llms.txt, Cash App llms-full.txt.
Both files include page descriptions pulled from frontmatter. Fern uses the description field if present, otherwise falls back to subtitle.
The output format depends on whether you’re requesting an individual page or a section:
Both llms.txt and llms-full.txt return the same format: