Reachable as plain text
Status code, redirect chain, content type, encoding and size, plus whether a companion llms-full.txt exists.
Free tool, no account
llms.txt checker
llms.txt checker
and validator.
Check an llms.txt file online for free. Enter a domain to inspect the live file, or paste a draft to validate its Markdown structure and link formatting in your browser. Review each issue before publishing.
Follows llms.txt proposal v2
Pasted drafts stay in your browser
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Checks
What gets checked
File reachability, Markdown structure, and link formatting.
The URL check inspects the file response. The validator reviews its contents; it does not visit every linked page or measure AI visibility.
Structure that parses
One H1 title first (after an optional byte order mark), no stray headings, and H2 sections that each hold a list. A missing summary is a recommendation, not a format error.
Links worth following
Every item is a Markdown link with an absolute URL. Duplicates, empty names, missing notes and off-site links are flagged.
A practical guide
The llms.txt format
The proposal fixes the order of a few Markdown elements. Everything else is up to you.
- An H1 title.
The only required element. It names the site or project and must come first, optionally preceded by a byte order mark:
# Example Company. - A summary blockquote.
One or two sentences straight after the title, starting with
>. It tells a model what the site is about before it reads any link. - Optional details.
Paragraphs or lists with context a reader needs, such as which version the docs describe. Any Markdown except headings.
- H2 sections of links.
Each
##section holds a list of- [Name](url): notesitems. A section namedOptionalmarks links that can be skipped. The proposal also supports files under a subpath, such as/docs/llms.txt; enter that full URL to check it.
| Level | Meaning | Examples |
|---|---|---|
| Error | The file breaks the format or cannot be read | No H1, two H1s, HTML instead of Markdown, 404, invalid URL |
| Warning | Readable, but likely to confuse a reader | No summary, empty section, relative URL, duplicate link, wrong content type |
| Info | Worth knowing, not a mistake | Redirects, off-site links, links without notes, no Markdown copies of pages |
What llms.txt can't do
- It is not a ranking signal. A valid file does not guarantee higher rankings or citations. The checker measures file structure, not visibility in search or AI answers.
- It does not control access. Blocking and allowing crawlers is the job of robots.txt, not llms.txt.
- It does not replace good pages. Keep linked pages accessible and clearly written. A format check does not confirm whether those pages are reachable or useful.
Tips for a useful file
- Curate, don't dump. List the pages that answer real questions, not every URL in your sitemap.
- Write notes. A few words after each link say when the page is the right one to read.
- Offer Markdown. The proposal suggests a clean
.mdcopy of key pages at the same URL plus.md. - Serve it as text. Use
text/plain; charset=utf-8ortext/markdown; charset=utf-8; both are read as text. Return a real 404 for missing files.
How the URL check works
When you enter a domain, our server requests /llms.txt from it with the user agent SeoVisionLlmsChecker/1.0, follows up to five redirects, and reads at most 512 KB. It also sends a HEAD request for /llms-full.txt. Private and internal network addresses are refused. Results are cached for ten minutes, so an edit you just published may take that long to show up. To test changes right away, use Paste content. Pasted text is checked in your browser and never sent to us.
Before you publish
llms.txt checker FAQ
What is llms.txt?
llms.txt is a proposed convention, published at llmstxt.org in 2024, for a Markdown file at the root of a site, or, since version 2 of the proposal, under a path such as /docs/llms.txt that covers the pages beneath it. It gives language models and AI tools a short, curated map of the pages that best explain the site: a title, a one-paragraph summary, and sections of links with short notes.
Will an llms.txt file improve my rankings or AI citations?
Not on its own. A valid llms.txt file does not guarantee higher search rankings or citations in AI answers. Treat it as a low-cost experiment that helps tools that do read it, and keep investing in crawlable, well-structured pages.
How is llms.txt different from robots.txt?
robots.txt tells crawlers what they may fetch. llms.txt does not allow or block anything; it only points to the content you consider most useful. A page blocked in robots.txt stays blocked even if llms.txt links to it.
What is llms-full.txt?
A companion file some sites publish next to llms.txt that contains the full text of the linked pages in one Markdown document. It is optional. The checker only reports whether it exists and how large it is.
Why does the checker fail when the file opens fine in my browser?
Common causes are a redirect to an HTML page, a soft 404 that returns your homepage with status 200, a firewall that blocks unknown user agents, or a wrong Content-Type header. The report shows the status code, redirect chain and content type so you can see which one applies.
Is the llms.txt checker free?
Yes, with no account. Fetched files are cached for ten minutes and are not stored after that. Pasted content is checked in your browser and never leaves your device.