This tool fetches your site's live /llms.txt file and checks it against the core structural rules of the llms.txt spec: a single H1 title at the top, a blockquote summary immediately beneath it, one or more H2 sections, and links formatted as - [title](url): description.
Why validation matters: llms.txt is meant to be parsed programmatically by AI systems, not just read by a human. A file that's missing the blockquote summary, uses the wrong heading levels, or has malformed links may be skipped or misread — silently defeating the purpose of publishing one in the first place. Since the spec is young and still evolving, small deviations are easy to introduce, especially if the file was hand-written or generated by a script that didn't follow the format closely.
How this tool works: enter your domain and the tool fetches https://yourdomain.com/llms.txt through a server-side proxy (to avoid browser CORS restrictions), then runs it through a rules-based structural check — no AI model is involved, so results are deterministic and instant. Each check reports pass or fail along with a short explanation of what was found or what's missing, and an overall score out of the total number of checks.
Limitations: this validator checks structural conformance to the llms.txt spec — it does not check whether your summary is well-written, whether you've linked the right pages, or whether any particular AI product actually fetches and uses your file. It also can't validate files that require authentication or aren't publicly reachable. If your file fails the fetch step entirely, double-check that it's served at the domain root with a 200 status and no redirect chain that a bot might not follow. For generating a compliant file from scratch, use the companion llms.txt Generator.