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llms.txt Checker

Check that your llms.txt file loads, follows the llmstxt.org format and links to pages that work. Enter your website, or paste the file to validate it in your browser.

Free, no sign-up. We load your-site/llms.txt, check its format and test the first 20 links.

How to check if a website supports llms.txt

Open https://the-domain.com/llms.txt in a browser. The site supports llms.txt if that address shows a plain text file that starts with a # heading. If you see the site's normal page, a not-found page or a download prompt, it does not, or the file is not served correctly.

A browser hides some problems, such as a wrong content type, a redirect to another domain or links to pages that no longer exist. Enter the site in the checker above to test those too.

What a valid llms.txt file looks like

The format comes from the llmstxt.org proposal. In order, a valid file has:

  • An H1 with the site or product name. This is the only required part.
  • A blockquote with a short summary, directly under the H1.
  • Optional paragraphs or lists with more context, without headings.
  • H2 sections, each with a list of links written as - [Page name](url): notes. The notes are optional.
  • An optional section named Optional for links an AI tool can skip when it needs a shorter context.
# Acme

> Acme turns meetings into searchable notes for product teams.

Acme works with Zoom, Google Meet and Microsoft Teams.

## Docs

- [Getting started](https://acme.com/docs/getting-started): Install Acme and record your first meeting
- [API reference](https://acme.com/docs/api): Endpoints for notes and transcripts

## Optional

- [Privacy policy](https://acme.com/privacy)

What this llms.txt checker tests

  • Delivery. That /llms.txt returns HTTP 200 as text/plain or text/markdown, not an HTML page, and does not redirect to another site.
  • H1 and summary. That the file starts with one H1 and has a blockquote summary under it.
  • Sections. That links sit in H2 sections. Sections with only text and H3 subheadings are noted, since tools that read the file use the links.
  • Link format. That every list item is a [name](url) link with a full URL, and no page is listed twice.
  • Links that load. When you check a website, we request the first 20 links and report broken pages, redirects and links that use http://.

Every check is a fixed rule; no AI reviews your file.

Common llms.txt errors and how to fix them

/llms.txt shows your website instead of the file

Single-page apps and many hosts send the homepage or a not-found page for any unknown path, with HTTP 200. Put the file in the folder your host serves from the site root, such as public in Next.js, Astro or Vite, and deploy again.

The file does not start with an H1

The first line must be # Your product, with one space after the #. Front matter, a title in bold or a blank heading do not count.

Links are not under H2 sections

Tools that read llms.txt look for links inside ## sections. Group your links under headings such as ## Docs and ## Product. H3 subheadings inside a section are fine; they are read as part of the H2 above them.

Relative or broken links

Write full URLs such as https://acme.com/pricing, not /pricing, and update links when you move or delete pages. The llms.txt generator can rebuild the list from your sitemap.

Wrong content type

If the file is served as application/octet-stream, browsers download it and some tools skip it. Set Content-Type: text/plain; charset=utf-8 for the path in your host or CDN settings.

FAQ

Is this llms.txt checker free?

Yes. There is no sign-up. Checking a website is limited to 10 checks an hour per visitor so the tool stays available; checking pasted text has no limit because it runs in your browser.

Is an llms.txt checker the same as an llms.txt validator?

Yes, people use both names for the same job: making sure the file follows the llmstxt.org format. This tool also checks the parts a format validator cannot see, such as how your server sends the file and whether the linked pages load.

Does it check llms-full.txt?

No. llms-full.txt is not part of the llmstxt.org proposal and has no agreed format, so there is nothing fixed to validate it against.

Does a valid llms.txt improve AI visibility?

No one has shown that it does. As of October 2026, none of the major AI companies has said its crawlers use llms.txt to choose which pages to cite. A valid file mainly helps AI coding tools and agents that look for it.

Do you store my file?

No. Website checks are not cached and the file is not saved. We keep a hashed, unreadable record of your IP address for up to a day for rate limiting. Pasted text never leaves your browser.

If you build an AI tool, an Ordalin listing is free and gives AI answers another researched page about your product to cite.