InstaRank SEO
Free AI Optimization Tool

Free LLMs.txt Checker — Validate Your /llms.txt File

Test your /llms.txt across 14 spec-grade parameters — H1 + blockquote, markdown link integrity, robots.txt cross-checks, AI bot accessibility (GPTBot, ClaudeBot, PerplexityBot, Google-Extended). AI-powered generator included.

How It Works

1

Enter Your URL

Type your website address above. We locate /llms.txt automatically at the root of your domain.

2

We Analyze

Our checker runs 14 LLMs.txt-native parameters — H1 + blockquote, link integrity, robots.txt cross-checks, AI bot accessibility, file structure.

3

Generate or Fix

Get your score, a prioritized issue list, and a one-click AI generator if you don't have an llms.txt yet (uses our centralized DeepSeek service).

What is llms.txt?

llms.txt is a markdown file placed at the root of your website (example.com/llms.txt) that gives AI agents — ChatGPT, Claude, Perplexity, Gemini — a curated guide to your most valuable content. Where robots.txt says "don't go here," llms.txt says "here's what matters most."

The standard was proposed in September 2024 by Jeremy Howard of Answer.AI. It's now adopted by Anthropic, Vercel, Cloudflare, Mintlify, Hugging Face and thousands of smaller sites. The format is intentionally minimal — pure markdown — so any LLM can parse it without specialized libraries.

The companion file llms-full.txt takes a different approach: it inlines the entire content of your site so AI agents that need depth can grab everything in one request. Most large adopters ship both.

The llms.txt spec at a glance

# Your Site Name

> One-sentence summary of the project — what it is, who it's for.

## Documentation

- [Getting Started](https://example.com/docs/start): The five-minute setup
- [API Reference](https://example.com/api): Full endpoint listing
- [Examples](https://example.com/examples): Working code samples

## Guides

- [Tutorial 1](https://example.com/tutorial-1)
- [Tutorial 2](https://example.com/tutorial-2)

## Optional

- [Changelog](https://example.com/changelog): Skippable for shorter context
- [Press Coverage](https://example.com/press)
  • Required: H1 with site/project name.
  • Recommended: Blockquote summary directly after H1.
  • Recommended: Each H2 section contains a list of markdown links.
  • Optional special section: A heading literally called ## Optional for content AI agents can skip if context budget is tight.
  • Best practice: File must be served as text/markdown or text/plain, never text/html.
  • Size: < 50 KB ideal, < 150 KB OK, ≥ 500 KB defeats the curation purpose — use llms-full.txt for bulk content.

The 14 parameters we check

1
File exists at /llms.txt
HTTP 200 at the root
2
Has H1 title
Spec's only required element
3
Has H2 + links
The actual curation payload
4
Linked URLs resolve
Up to 25 sampled, 200 OK
5
Blockquote summary
Spec-recommended second element
6
Correct Content-Type
text/markdown or text/plain
7
No duplicate links
Wastes AI context window
8
Markdown link format
No bare URLs, HTML anchors, or "click here"
9
No auth-walled links
No 401/403 or login redirects
10
Healthy file size
<50KB ideal, <150KB OK
11
Not robots-blocked
Linked URLs crawlable per robots.txt
12
AI bots allowed
GPTBot, ClaudeBot, PerplexityBot, Google-Extended
13
llms-full.txt companion
Bonus — fallback for depth
14
Discovery link tag
Bonus — <link rel="llms"> in HTML head

Best practices

  • ✓
    Curate, don't dump. An llms.txt with 30 high-quality links beats one with 300 noisy ones. AI agents allocate fixed context budget.
  • ✓
    Group by intent. Use H2 sections that match how a user would ask: "Documentation," "Pricing," "Examples," "API Reference."
  • ✓
    Use absolute URLs. Spec allows relative URLs, but absolute ones survive non-root deployments and partial fetches.
  • ✓
    Add descriptions after a colon. [Quickstart](url): 5-minute setup beats a bare title — gives the AI signal about what each link is for.
  • ✓
    Don't block AI bots in robots.txt. Having an llms.txt while blocking GPTBot / ClaudeBot / Google-Extended is self-defeating.
  • ✓
    Ship llms-full.txt too. For documentation-heavy sites, the full-content fallback unlocks better AI answers when context allows.
  • ✓
    Update quarterly. Treat it like a sitemap — refresh when navigation changes or major content launches.

Frequently asked questions

Will AI agents actually read my llms.txt?

Major AI tools — ChatGPT browse mode, Claude, Perplexity, Gemini — check /llms.txt at inference time when answering site-specific queries. Adoption is growing fast. Even where adoption is partial, the cost is zero and the upside is direct control over how AI describes your product.

Should I block AI bots OR have an llms.txt?

They serve opposite purposes. If you publish an llms.txt, allow AI bots (GPTBot, ClaudeBot, PerplexityBot, Google-Extended) in robots.txt. If you actively want to keep AI agents out, block them in robots.txt and don't publish an llms.txt.

Can I autogenerate it?

Yes — our generator crawls your site, picks the top ~50 pages, then uses AI (DeepSeek primary, Gemini fallback) to write a spec-conformant llms.txt with curated sections. Edit before publishing. 50 credits per generation; refunded if AI fails.

Where exactly does it live?

HTTPS root: https://yourdomain.com/llms.txt — same convention as robots.txt and sitemap.xml. Subdirectory paths like /docs/llms.txt are not part of the spec.

What's the difference from sitemap.xml?

sitemap.xml is for traditional search-engine crawlers and lists every indexable URL. llms.txt is for AI agents at inference time and lists the curated subset you want them to load when answering questions about your site.

Want a complete AI + SEO audit?

LLMs.txt is one of 20 checks we run. Get the full picture — robots.txt, sitemaps, meta tags, page speed, content quality, internal links, E-E-A-T, AI visibility — in one report.

Run Full Website Audit