llms.txt Validator

What is an llms.txt validator?

An llms.txt validator reviews the llms.txt file published on your site, helping AI tools understand the content you want them to find. Introduced in 2024, llms.txt is a Markdown document at your domain’s root that provides language models with a hand-picked guide to important pages. This tool reads that document and identifies structure that does not follow the expected format.

Since the convention is still emerging, it is easy to overlook a heading, include an invalid URL, or format a section incorrectly. Checking the file before release gives AI crawlers and assistants a clear, usable map instead of a document they may misread. It works like a linter for the pages that matter most on your website.

How to validate your llms.txt file online

1. Paste your file. Copy its contents into the tool and validate it locally in your browser.

2. Validate by URL. Enter a domain and the validator fetches its public /llms.txt file for review.

The result includes a 0–100 health score plus actionable errors, warnings, and suggestions.

What this llms.txt validator checks

It checks the practical parts of a useful llms.txt file:

• H1 title. A single clear project or site name.
• Summary blockquote. A concise explanation for AI systems.
• Link sections. Markdown links grouped under ## headings.
• Valid URLs and descriptions. Clear destinations and context.
• Optional section. Kept last when present.

Why use an llms.txt validator?

A clean file gives AI-assisted tools a clearer path to your documentation, product pages, guides, and other high-value content. Validation turns a guess into a repeatable quality check.

The score and suggestions also make the format easier to maintain as your site changes.

When should you run the validator?

Validate when you first create llms.txt, then again after moving documentation, changing important routes, adding product areas, or removing pages referenced by the file.

Keeping it current matters more than making it long: a short, accurate map is more useful than a stale one.

llms.txt format the validator expects

A useful file opens with an H1, a short summary, and one or more sections of descriptive links.

# Example Project

> A one-sentence summary of the site for AI systems.

## Docs
- [Getting started](https://example.com/start): setup guide
- [API reference](https://example.com/api): full reference

## Optional
- [Changelog](https://example.com/changelog): release history

Load the sample above to study and adapt this structure.

llms.txt validator vs llms.txt checker

Both names mean the same thing here: checking whether your file is structured clearly enough for AI systems to use it.

Common llms.txt errors the validator catches

Common problems include a missing or duplicated H1, malformed links, empty sections, vague descriptions, and an Optional section placed before required content.

Is the llms.txt validator private and free?

Yes. The tool is free. Pasted text is processed locally; URL mode only reads the public file you request.