llms.txt Validator

About the llms.txt Validator

Publishing an llms.txt file is only half the job; a file with a missing title, HTML mixed into the markdown, or links in the wrong format may be silently ignored by the very tools it was written for. This llms.txt validator reads your file the way a strict parser would, checking it against the specification rule by rule and showing you exactly which lines need attention.

You can validate in whatever way matches your workflow: fetch the live file from any public website by URL to confirm what the world actually sees, paste a draft while you are still writing it, or upload the file from your computer. The checks run against the real specification: one H1 title, a blockquote summary, links grouped under H2 sections, full URLs, no duplicates, and an Optional section that is spelled exactly as the standard expects.

If the check shows your site has no llms.txt at all, the companion llms.txt generator creates one with the correct structure from the start, so most of these errors never happen. Used together, the two tools cover the whole job: build the file, prove it is valid, and re-check it whenever your important pages change.