llms.txt validator
Check that your llms.txt is a real text file in the right format: one title, a short summary, sections with links, and links that still work. Test the live file of a site, or paste a draft before you upload it.
Or ask your AI assistant
This check is the validate_llms_txt tool in the free OnPage.dev MCP server. Connect it to Claude, ChatGPT or Cursor once, then ask in your own words.
Check the llms.txt of example.com with OnPage.dev and fix what is wrong.
validate_llms_txt/llms.txt returns an HTML pagegenerate_llms_txtNew llms.txt with 28 pages
What gets checked
- Whether
/llms.txtis a text file at all. Many sites answer with their normal HTML page or a soft 404, which AI tools cannot use. - One
#title on the first line, and a>summary right below it. ##sections with links written as- [Name](url): note.- Whether up to 8 of the linked pages load, and whether they redirect.
- The file size, and whether an
llms-full.txtexists next to it.
llms.txt is a proposal, not an official standard, so these checks follow the format described on llmstxt.org. No file yet? Make one with the llms.txt generator.
Questions
Why does my llms.txt fail when the file exists?
Usually because the address returns an HTML page instead of the text file, for example when a CMS shows its 404 page with status 200. Open the address in a browser: you should see plain text, not your site.
Do I also need llms-full.txt?
No. It is optional. llms-full.txt holds the full text of your key pages in one file, while llms.txt is the short index.
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