llms.txt checker
Validate your /llms.txt file against the llmstxt.org specification. Check for the required H1, blockquote summary, H2 sections, link format, and more.
What is llms.txt?
The llms.txt file is a markdown file served at /llms.txt that provides LLM-friendly content about your website. It acts as a machine-readable index, similar to how sitemap.xml works for search engines, but optimised for AI agents and language models.
Why adopt it
Without /llms.txt, LLMs have to scrape and guess at what your site is for, which hurts citation accuracy. With it, ChatGPT-style agents get a curated, link-rich index to the pages you actually want them to cite - cheaper than rewriting your whole site for LLM-friendly navigation, and the only standard currently in wide use across docs sites.
What we check
- File is accessible at /llms.txt (HTTP 200)
- Starts with an H1 heading (project/site name)
- Contains valid, parseable markdown
- Has a blockquote summary below the H1
- Includes H2 sections with file lists
- Links use the correct [name](url) format
- Linked URLs are accessible
- Content-Type is text/plain
- llms-full.txt variant is available
Minimal valid example
# Acme Cloud Widgets
> Widgets-as-a-service for serverless apps. Deploy in one command.
## Docs
- [Getting Started](https://acme.dev/docs/start.md): zero-to-deployed in 60s
- [API reference](https://acme.dev/docs/api.md): REST endpoints and auth
## Examples
- [Node.js quickstart](https://acme.dev/examples/node.md)H1 title, blockquote summary, H2 sections with [name](url) links. That’s the whole spec.