llms.txt file: a standard for LLM visibility

1. llm.txt File Accessibility
2. llm.txt File Format (MIME Type)
3. llm.txt File Content and Structure
4. Useful Resources and Links

1. llm.txt File Accessibility

The llm.txt file is a new standard proposed to allow developers to control how large language models (LLMs) and generative AI engines access and interpret a website's content. Its presence and accessibility are fundamental for effective GEO optimization.

• Location: The llm.txt file must be located at the root of the domain. It can be named /llm.txt or /llms-full.txt. For example, for the domain example.com, the file must be accessible via https://example.com/llm.txt or https://example.com/llms-full.txt.
  ‍
• HTTP/HTTPS Accessibility: The file must be accessible via both HTTP and HTTPS protocols. It is recommended to ensure that the HTTPS version is the canonical version and that any HTTP requests are redirected to HTTPS.
  ‍
• HTTP Status Code: The server must return an HTTP 200 OK status code when requesting the llm.txt file. A 404 Not Found or any other error code will prevent LLM from processing your directives.

2. llm.txt File Format (MIME Type)

To ensure correct interpretation by AI engines, the llm.txt file must be served with the appropriate MIME type.

• MIME Type: The server must return the llm.txt file with the text/plain MIME type. Any other MIME type could cause the file to be incorrectly interpreted or rejected by LLMs.
  ‍
• Encoding: The file must be encoded in UTF-8 to ensure compatibility with all characters and avoid interpretation issues.

• Minimum Content: The llm.txt file must not be empty. At a minimum, it should contain a title and a brief summary to indicate its function and content.

3. Content and Structure of the llm.txt File

The llm.txt file should be structured to provide clear and concise information to AI models. It should include a title, a summary, detailed sections, and relevant links.

Title: The file should begin with a clear title, using Markdown Level 1 format (#). This title should reflect the main topic of the document.

# Title of the llm.txt documentation

‍

Brief Summary: Include a brief summary at the beginning of the file, just after the title. This summary should contain the key information needed for an LLM to understand the rest of the file, such as the site's purpose or the type of content it offers.
‍

Sections: The file should be organized into clear sections, using level 2 or 3 headings (## or ###). Each section can contain paragraphs or lists to introduce key elements of the site, such as the topics covered, featured products, or services offered. Example section:

## About our company. Our company specializes in [business description]. We offer [list of products/services].

‍

Links to Markdown pages: The file should contain links to important pages on your site, formatted in Markdown. These links allow LLMs to discover and explore relevant content in a structured way. Example link:

To learn more about our services, visit our [services page](https://www.example.com/services).

‍

Link notes: Add notes or short descriptions for each link to provide additional context for LLMs. This helps them understand the relevance of the linked content. Example note:

[Services page](https://www.example.com/services): Learn about our full offerings and how we can help you.

Resources & useful links

• Standard llmstxt.org - official documentation