Free tool
llms.txt validator
This validator fetches /llms.txt from any domain and checks it against the llmstxt.org format: one H1 with the site name, a blockquote summary, then H2 sections of markdown links. Every deviation gets listed. An honest caveat up front: the evidence that engines read this file is weak, and the case for validating one is simply that a file you choose to publish should be correct.
What the evidence says about llms.txt
Read the numbers before investing time here. Ahrefs studied 137,000 domains in 2026 and found about 97 percent of llms.txt files receive zero bot hits, meaning the crawlers the file was written for almost never fetch it. Google has said it does not use the file, and Google's John Mueller publicly compared it to the keywords meta tag, a self-declared description with no consumer on the other end. No major engine has committed to reading it.
So why offer a validator? Because the file costs almost nothing to serve, a handful of smaller tools and agents do fetch it, and the downside case is specific: a malformed or stale llms.txt is worse than none, since anything that does read it receives broken guidance under your brand's name. If you ship the file, ship it correct and current. If you skip it, you are skipping something with no demonstrated cost.
What the format requires and how to read your results
The llmstxt.org spec is short. The file starts with a single H1 naming the site or project. An optional blockquote directly under it carries a one-paragraph summary, and the spec treats that summary as the highest-value line in the file. Plain prose may follow. Then come H2 sections, each containing a markdown list of links in the form of a bracketed name, a URL, and an optional colon-separated description. A section titled Optional has defined meaning: readers may skip it when context is tight.
The validator flags structural breaks in that order: a missing or duplicated H1, a summary that is ordinary text rather than a blockquote, link lines that fail to parse, empty sections, and URLs that point at redirects or errors. Fix the H1 and blockquote first since they anchor the parse, then repair dead links, then trim sections that list every page on your site, because a curated dozen links serves the format's purpose and a dump defeats it.
Frequently asked questions
Will llms.txt improve my AI visibility?+
The honest answer is that there is no evidence it will. Ahrefs' 137,000-domain study found roughly 97 percent of these files get zero bot hits, and Google says it does not use the file. Visibility gains come from crawlable pages that answer buyer questions well. Treat llms.txt as a low-cost courtesy file, and spend your real effort on content.
Should I delete my llms.txt if nothing reads it?+
Keeping it is fine as long as it stays accurate, since serving a small text file is free and a few agents and tools do fetch it. The maintenance rule is the point: dead links and outdated descriptions in the file misinform exactly the readers who bothered to fetch it. If nobody owns keeping it current, removing it is the cleaner choice.
What are the most common format mistakes?+
Four dominate. Writing the summary as plain text instead of a blockquote, so parsers miss the one line the spec values most. Skipping the H1 or adding several. Link lists that break markdown syntax, usually bare URLs without the bracketed name. And treating the file as a sitemap by pasting hundreds of links, which discards the curation that gives the format any point.
If llms.txt barely matters, what actually moves AI visibility?+
Three layers with real evidence behind them. Access: AI crawlers must be able to fetch your pages, and CDN rules silently block them on many sites. Content: pages that answer specific buyer questions get retrieved and quoted. Measurement: you need to know which questions you win. Reachroller covers that last layer, tracking whether ChatGPT names your brand, from $29 per month with a free 3-day trial.
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