Free tool
LLMs.txt Checker
Whether your site has an llms.txt file, and a line-by-line read of what is in it.
How it works
What is the LLMs.txt Checker?
The LLMs.txt Checker is a free tool that looks for /llms.txt and /llms-full.txt at the root of a website and reports whether each file is found, with its size and last-modified date when the server sends one. It then runs a content check on the llms.txt file and lists any errors or warnings.
How to use the LLMs.txt Checker
- Enter the website's domain, such as example.com. The tool checks the root of the domain, where both files live.
- Press Check LLMs.txt. The tool requests /llms.txt and /llms-full.txt from that site.
- Read the Domain Check tab: found or not found for each file, its URL, and its size and last-modified date when available.
- Open the Content Validator tab to see the line counts, errors and warnings for the llms.txt file that was served.
What is llms.txt used for?
llms.txt is a markdown file at /llms.txt that points language models to the pages on a site worth reading. It starts with an # H1 naming the site, an optional > blockquote summary, then ## Section headings, each holding a list of links written as - [Name](https://example.com/page): what it covers.
It is a curated map, not a sitemap. The point is that a person chose the twenty pages worth reading instead of listing all twenty thousand. A companion file, llms-full.txt, puts the full text of those pages into one file so a model can read the content without fetching each link.
Is llms.txt actually used by AI search engines?
Not as far as anyone has confirmed. llms.txt is a proposal published by Jeremy Howard of Answer.AI in September 2024, not a standard. No major AI provider has publicly confirmed that its crawlers read it, and Google's John Mueller has compared it to the keywords meta tag.
Treat it accordingly: quick to publish, no downside, and no evidence it changes anything on its own. It also cannot make up for pages a crawler cannot reach. If your content is blocked in robots.txt or only renders with JavaScript, listing it in llms.txt changes nothing, because something still has to fetch those pages.
How do I check if a site has an llms.txt file?
Open the domain followed by /llms.txt in a browser, or run this checker, which requests both /llms.txt and /llms-full.txt at once and reports whether each one is found.
When you open the file yourself, you should see plain markdown, not a styled page or your 404 page. Hosts with catch-all routing can answer every path with an HTML page, so check the content as well as the address. The file should be served as text/plain or text/markdown.
Questions
- Is llms.txt worth it?
- An llms.txt file is worth publishing if you have documentation or a handful of pages that explain what you do, because it takes minutes and has no downside. Do not expect it to change anything measurable on its own: no major AI provider has confirmed reading it.
- Does Google use llms.txt?
- Google has not said it uses llms.txt, and its Search Advocate John Mueller has compared the file to the keywords meta tag. Google says pages need no special files or markup to appear in AI Overviews, and normal SEO practice applies.
- What is the difference between llms.txt and robots.txt?
- robots.txt tells crawlers which URLs they may fetch, and crawlers that follow the standard respect it. llms.txt is a reading list of the pages a site wants language models to see. It allows or blocks nothing, and nothing enforces it.
- What is the difference between llms.txt and llms-full.txt?
- llms.txt is an index of links, while llms-full.txt contains the full text of those pages in one file. That makes llms-full.txt far larger. It suits sites whose documentation is the product, and most sites need only llms.txt.
- Where does the llms.txt file go?
- The llms.txt file goes at the root of the domain, so it loads at example.com/llms.txt. Nothing links to it and no header announces it, so a copy in a subdirectory will not be found.
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