Free tool
llms.txt Validator
Paste your file or enter a domain. We check it against the llms.txt spec — title, summary, sections, and links — and tell you exactly what to fix.
We look for /llms.txt at the domain root.
What this checks
An llms.txt file is a markdown file at your site root that points language models to your most important pages. A valid file has one H1 title, a blockquote summary, optional detail prose, then H2 sections containing curated [name](url) link lists. This validator flags missing or duplicate titles, a missing summary, empty sections, malformed link URLs, and headings deeper than H2 — and scores the result out of 100.
llms.txt vs llms-full.txt
llms.txt is the concise index — a curated map of links. llms-full.txt is the optional, larger companion that inlines the actual content so a model has everything in one fetch. Keep the index short and move bulk content into the full file. For the full breakdown, read llms.txt explained.
Want to be cited by AI search, not just validate a file?
A clean llms.txt is one signal. Getting ChatGPT, Perplexity, and Google AI Overviews to cite you is the work — answer-first content, schema, and entity coverage. That's our generative engine optimization practice.