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llms.txt Validator

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Validate any llms.txt file against the community spec — paste content or fetch a URL. Get H1/summary/section/link checks, size warnings, and line-level errors.

Spec Checks
Paste or URL
SEO + AI
Line Errors
Paste llms.txt content above, load the example, or fetch a URL to validate.

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  src="https://tools.town/embed/llms-txt-validator/"
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  title="llms.txt Validator">
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How to Use

  1. 1 Paste your llms.txt contents — or switch to Fetch URL and enter your domain
  2. 2 Review the pass/fail banner, stats (H1, sections, links, size), and issue list
  3. 3 Fix errors first (missing H1, malformed list links, extra headings)
  4. 4 Address warnings (missing summary, relative URLs, large file size)
  5. 5 Re-validate, then deploy the file to https://yoursite.com/llms.txt

Features

  • Validates against the llmstxt.org community format
  • Paste mode for local files — nothing uploaded for validation
  • URL fetch via CORS-safe proxy for live /llms.txt checks
  • Line-level errors, warnings, and info notes
  • Stats: H1 title, summary, sections, absolute vs relative links, Optional section
  • File size warnings when you should split into llms-full.txt

Why it Matters

llms.txt is a curated Markdown index so AI agents know which pages matter on your site. A malformed file is silently ignored or misread. This validator catches missing H1s, bad list links, relative URLs, and oversized files before you deploy.

★★★★★

Use Cases

SEO / GEO teams

Ship a correct AI-readable index alongside robots.txt and sitemaps

Docs & API products

Point agents at your real docs paths — getting started, auth, reference

Launch checklist

Validate before go-live so /llms.txt is ready the day you ship

Agency audits

Fetch a client domain and score their llms.txt in seconds

What this tool does

Check that your /llms.txt follows the llmstxt.org Markdown format: H1 first, optional blockquote summary, and H2 sections whose lists are annotated links. Paste a file or fetch a live domain and fix issues before agents waste context on a broken index.

Minimal valid example

# Acme Docs

> Acme's public documentation and API for product teams and developers.

## Docs

- [Getting Started](https://acme.example/docs/start): Install and first request
- [API Reference](https://acme.example/docs/api): Endpoint catalogue

Use the robots.txt Generator for crawl rules and the sitemap.xml Generator for search discovery — then keep llms.txt as the curated AI-facing overview.

Frequently Asked Questions

Is it llms.txt or llm.txt?
The community specification at llmstxt.org uses the plural form llms.txt (with an s), served at the site root. People often type llm.txt by habit — this tool validates the standard llms.txt format.
Does llms.txt block AI crawlers?
No. llms.txt is a curated reading list for agents. To block crawlers or training bots, use robots.txt (and this site's robots.txt Generator). The two files solve different problems.
Is the fetch URL feature uploading my content?
Paste mode never leaves your browser. URL mode only asks our proxy for the remote file so your browser can bypass CORS; we do not store the body beyond the request lifetime.
What is the Optional section?
An H2 titled exactly Optional marks secondary links agents may skip when context is limited. Our validator treats that title specially and reports it as info.
Should absolute URLs be required?
The spec allows relative links, but most validators (including this one) warn on relative URLs because they break when the file is copied or mirrored without a base origin.
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Want to understand the math?

Browse all guides →
llms.txt Explained
llms.txt

llms.txt Explained: Complete Guide for AI Discovery and GEO

What /llms.txt is, the Markdown format from llmstxt.org, how it differs from sitemaps and robots.txt, writing tips, llms-full.txt, and how to validate before you deploy.

5 Aug 2026

11 min read

llms.txt vs robots.txt
llms.txt

llms.txt vs robots.txt: What Each File Does (and Does Not Do)

Clear comparison of llms.txt and robots.txt — curated AI indexes vs crawl control, misconceptions about blocking AI, how they work with sitemaps, and when you need both.

5 Aug 2026

9 min read

How to Create an llms.txt File
llms.txt

How to Create an llms.txt File (Step-by-Step)

Create a compliant /llms.txt from scratch: draft H1 and summary, pick sections and absolute links, validate with tools.town, deploy to the site root, and verify in the browser.

5 Aug 2026

8 min read

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