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The llms.txt file is an industry standard that helps large language models (LLMs) index content more efficiently, similar to how a sitemap helps search engines. AI tools can use this file to understand your documentation structure and find content relevant to user queries. Mintlify automatically hosts an llms.txt file at the root of your project that lists all available pages in your documentation. This file is always up to date and requires zero maintenance. You can optionally add a custom llms.txt file to the root of your project.
Authentication affects llms.txt and llms-full.txt differently depending on your site configuration:
  • Fully authenticated sites: Both files require authentication. AI tools that cannot authenticate cannot access them.
  • Partially authenticated sites: Both files are publicly accessible, but only list public pages and exclude pages restricted to user groups.
For more information on how authentication affects AI features, see Feature availability.
View your llms.txt by appending /llms.txt to your documentation site’s URL. Mintlify also hosts the file at /.well-known/llms.txt for compatibility with tools that follow the .well-known convention. Mintlify adds HTTP headers to every page response so AI tools can discover your llms.txt files and other agent resources without prior knowledge of their location:
  • Link: Follows the standard HTTP Link header format for resource discovery. Advertises llms.txt, llms-full.txt, your API catalog, MCP server card, agent card, and agent skills index.
  • X-Llms-Txt: A convenience header for tools that check for llms.txt support.
Response headers
Sites that use authentication also advertise their OAuth protected resource metadata with rel="oauth-protected-resource". If you serve your documentation under a base path, every advertised path includes that prefix.

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Structure of the llms.txt file

An llms.txt file is a plain Markdown file that contains:
  • Site title as an H1 heading.
  • Site description as a blockquote summary below the title, sourced from the description field in your docs.json configuration.
  • Custom agent instructions as an Agent Instructions block after the description, if you set markdown.instructions in your docs.json.
  • Structured content sections with links and a description of each page in your documentation.
  • API specification links to your OpenAPI and AsyncAPI specs, if your documentation includes them.
  • External links in an Optional section, for any absolute URLs in your navigation.
The llms.txt file lists your pages in the order they appear in your docs.json navigation. Pages that aren’t in your navigation but that seo.indexing: "all" includes appear last, in alphabetical order. Page links in the llms.txt file include a .md extension so AI tools can fetch the Markdown version of each page directly. Each page’s description comes from the description field in its frontmatter. Mintlify uses the first paragraph of the description and truncates it at 300 characters. Pages without a description field appear in the llms.txt file without a description. Both llms.txt and llms-full.txt list pages from your default language and default version. They exclude hidden pages and pages with noindex: true in their frontmatter unless you set seo.indexing: "all" in your docs.json. This structured approach allows LLMs to efficiently process your documentation at a high level and locate relevant content for user queries, improving the accuracy and speed of AI-assisted documentation searches.

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Split indexes under /_llms

Automatically generated llms.txt index files cannot exceed 100,000 characters. When an index is larger than this limit, Mintlify keeps the main llms.txt file as a directory and moves groups of page links into generated Markdown files under /_llms/. Every page stays discoverable: splitting never omits pages from the index. This limit does not apply to llms-full.txt. Links to generated indexes appear in an Indexes section. Each link includes the group’s breadcrumb, its page count, and a description:
A generated index can link to further indexes. For example, /_llms/api-reference.md can link to /_llms/api-reference/admin.md when a group is too large for a single file. Agents should follow these index links recursively until they reach documentation page links. Mintlify may shorten page descriptions in a split index to keep each file under the character limit. The generated files are part of llms.txt and do not need to exist in your repository. They are separate from llms-full.txt. The /_llms/ route uses the same base path as your documentation:
  • A root-hosted site serves an index at https://docs.example.com/_llms/api-reference.md.
  • A site hosted at /docs serves it at https://example.com/docs/_llms/api-reference.md.
If you use a reverse proxy or path allowlist, forward the generated route in addition to llms.txt. A broad <base-path>/* rule already includes <base-path>/_llms/*. With granular rules, add <base-path>/_llms/* explicitly. See Reverse proxy for routing guidance.
A directory such as /docs in your repository does not set your site’s public base path. Configure the base path in your Mintlify dashboard and use the same prefix in your reverse proxy. Otherwise, llms.txt can be reachable at the public prefix while its generated /_llms/ links point somewhere else.
Example llms.txt

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llms-full.txt

The llms-full.txt file combines your entire documentation site into a single file as context for AI tools and LLM indexing. Each page appears as its title, source URL, description, and full Markdown content. Mintlify automatically hosts an llms-full.txt file at the root of your project. View your llms-full.txt by appending /llms-full.txt to your documentation site’s URL. Mintlify also hosts the file at /.well-known/llms-full.txt for compatibility with tools that follow the .well-known convention.

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Custom files

To add a custom llms.txt or llms-full.txt file, create an llms.txt or llms-full.txt file at the root of your project. Adding a custom file overrides the automatically generated file of the same name. If you delete a custom file, Mintlify restores the automatically generated file. Your custom llms.txt or llms-full.txt file must have a site title as an H1 heading. Other content is optional. See Format in the llms.txt specification for more information on optional sections and best practices.
On sites that use authentication, custom llms.txt and llms-full.txt respect authentication.If a custom file links to any page that isn’t public, only authenticated users can access the file. Anonymous visitors receive the automatically generated llms.txt or llms-full.txt, which only include publicly available links.

Related topics

GEO guide: Optimize docs for AI search and answer enginesGlossaryMintlify CLI command reference