LLMs.txt Validator
Get mentioned by AI assistants
MentionAgent helps your brand get cited by ChatGPT, Claude, and other AI models through strategic link building and content placement.
Start Getting Mentioned For $99/moWhat this tool validates
| Check | Severity | What it means |
|---|---|---|
| H1 heading present | Required | Your file must start with a # Site Name heading to identify your site. |
| Blockquote description | Required | A > description line gives AI models a quick summary of your site. |
| Contains links | Warning | At least one [text](url) link helps AI models find your key pages. |
| Section headings | Warning | ## Section headings organize your content into logical groups. |
| Valid URL format | Warning | All links should use valid URL patterns starting with http:// or https://. |
| No HTML tags | Warning | llms.txt should be plain Markdown, not HTML. |
| File not empty | Required | An empty file provides no value to AI models. |
| Reasonable length | Warning | File should be long enough to be useful but not excessively large. |
llms.txt format reference
The llms.txt file uses a simple Markdown-based format. Here is the basic structure:
# Your Site Name > A brief description of what your site does. - [Homepage](https://example.com) ## Key Pages - [About](https://example.com/about): Learn more about us - [Pricing](https://example.com/pricing): Plans and pricing - [Blog](https://example.com/blog): Latest articles ## Topics - Topic One - Topic Two
The H1 heading and blockquote description are required. Section headings (##) and links are recommended. The file should be plain Markdown with no HTML tags. Place the file at yourdomain.com/llms.txt.
Frequently asked questions
What is llms.txt validation?
llms.txt validation is the process of checking whether your llms.txt file follows the correct format and includes all required elements. A validator checks for proper Markdown structure, required sections like the H1 heading and description blockquote, valid link formatting, and overall content quality.
What makes a valid llms.txt file?
A valid llms.txt file must include an H1 heading (# Site Name) and a blockquote description (> description). It should also contain links in Markdown format [text](url), section headings (## Section), and be written in plain Markdown without HTML tags.
Is llms.txt required for AI visibility?
While not strictly required, llms.txt is a recommended best practice for AI visibility. It helps AI models like ChatGPT, Claude, and Gemini understand your website's content and structure. Having a well-formatted llms.txt file is a simple step that can improve how AI assistants reference your brand.
How often should I update my llms.txt?
Update your llms.txt whenever you make significant changes to your site — such as adding new key pages, changing your site description, or restructuring your content. A good rule of thumb is to review it quarterly or whenever you update your sitemap.