llms.txt Validator
Check an existing llms.txt file by URL or pasted text.
Use this llms.txt validator to check whether your file follows the emerging llmstxt.org structure. You can fetch a live /llms.txt by URL or paste content directly into the checker. The validator highlights missing required elements, malformed markdown links, structural warnings, improvement suggestions, and optional link status.
Enter a domain and we’ll look for /llms.txt, or paste a direct link to a .txt file.
How to validate an llms.txt file
- Enter a domain or URL. Use URL Input to fetch a live file from your site, or paste a direct link to an existing
llms.txt. - Run the check. The validator parses the markdown structure and compares it with the llms.txt format.
- Review issues. Fix required errors first, then warnings and improvement suggestions.
- Check links. If your file includes URLs, run the optional link checker to confirm they resolve.
What the validator checks
Required H1 title
A valid file should start with one clear project or site title.
Summary blockquote
A short blockquote helps AI tools understand the site quickly.
Grouped links
H2 sections should contain useful markdown links with optional notes.
Markdown format
The checker flags list items and links that are difficult to parse.
Live preview
See how your llms.txt will be interpreted after parsing.
Link health
Optionally test linked pages to catch broken or unreachable URLs.
Common llms.txt mistakes
- Publishing the file somewhere other than the domain root.
- Using a sitemap dump instead of a curated list of important pages.
- Missing the H1 title at the top of the file.
- Adding bare URLs instead of markdown links with clear labels.
- Mixing too many localized duplicates into one file.
- Letting old documentation or product links go stale.
Valid llms.txt example
A minimal valid file can look like this:
# Title > Optional description goes here Optional details go here ## Section name - [Link title](https://link_url): Optional link details ## Optional - [Link title](https://link_url)
Frequently asked questions
What does the llms.txt validator check?
It checks the required H1 title, optional summary and sections, markdown link formatting, suggestions, preview rendering, and optional link health.
Can I validate pasted llms.txt content?
Yes. Use Text Input to validate pasted content directly in your browser.
Where should my llms.txt file be published?
Publish it at the root of your domain, usually https://yourdomain.com/llms.txt, so AI tools and agents can discover it predictably.
Is an invalid llms.txt file bad for SEO?
llms.txt is not a confirmed Google ranking factor. Validation still matters because a clean, predictable file is easier for AI assistants, agents, and tooling to parse.