LLMS.txt Checker – Free Online Validator (2026)

Q: Where do I put my llms.txt file?

At your domain root: https://yoursite.com/llms.txt, served as plain text.

Q: What is the difference between llms.txt, robots.txt and sitemap.xml?

robots.txt controls crawler access, sitemap.xml lists URLs for search crawlers, and llms.txt is a curated Markdown index that suggests priority pages and context to AI systems.

Q: Is there a size limit?

The spec has no hard limit, but keep it concise. Split full page text into llms-full.txt and keep llms.txt as the curated overview.

We try to fetch /llms.txt from the domain you enter. If the site blocks cross-origin reads, use the “Paste file content” tab instead.

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What is llms.txt?

llms.txt is a proposed standard (llmstxt.org, 2024) — a Markdown file at your domain root that tells AI systems which pages matter most on your site. Think of it as robots.txt for access control and sitemap.xml for crawlers, but written for how language models read: a clear # H1 site name, a > summary, and ## section-grouped lists of links with short descriptions.

Minimal valid example

# Acme Docs

> Developer documentation for Acme's API and SDKs.

## Guides
- [Quickstart](https://acme.com/docs/quickstart): get running in 5 minutes
- [Authentication](https://acme.com/docs/auth): API keys and OAuth

## Optional
- [Changelog](https://acme.com/changelog): what's new

FAQ

Where do I put my llms.txt file?

At your domain root: https://yoursite.com/llms.txt, served as plain text. For docs-only coverage you can also place it under a subdomain like docs.yoursite.com/llms.txt.

What is the difference between llms.txt, robots.txt and sitemap.xml?

robots.txt controls which crawlers may access which paths. sitemap.xml lists URLs for search crawlers. llms.txt is a curated, human-readable index that suggests priority pages and context to AI systems. They complement each other.

Does llms.txt improve my Google rankings?

There is no confirmed ranking effect. Its purpose is helping AI assistants and agents understand and cite your content accurately — relevant for AI-driven discovery rather than classic SEO.

How often should I update llms.txt?

Whenever important pages move, get renamed, or new flagship content launches. Re-run this checker after each update to catch broken links or drift from the spec.

Is there a size limit?

The spec has no hard limit, but keep it concise — it should be an index, not a dump. If it grows large, split full page text into llms-full.txt and keep llms.txt as the curated overview.

Is my content uploaded anywhere?

No. Every check runs locally in your browser via JavaScript. In URL mode we fetch the public file directly from the site you enter — nothing is stored or sent to our servers.