llms.txt vs robots.txt: What Each Does for AI

Published: June 13, 2026

Both llms.txt and robots.txt live at your site root, and both are read by bots, so it is easy to assume they do the same job. They do not. One controls access. The other describes content. You want both, and this guide explains exactly what each does.

The short answer

robots.txt tells bots what they are allowed to crawl. llms.txt tells AI assistants what your site is about. The first is a gate. The second is a summary. They solve different problems, so one does not replace the other.

What robots.txt does

robots.txt is the older standard, and every well-behaved crawler checks it first. It is an access-control file. Each rule names a user-agent and lists the paths that agent may or may not crawl.

User-agent: GPTBot
Allow: /
Disallow: /members/

User-agent: *
Allow: /

Sitemap: https://yoursite.com/sitemap.xml

That is the whole purpose: permission. It does not describe your business, summarize your content, or tell the bot what you sell. It only answers one question for each crawler, which is whether it is allowed to read a given path.

What llms.txt does

llms.txt is the newer standard, built for AI assistants. It is a content summary written in markdown. It gives the AI a clean, structured description of your site so it does not have to infer everything from your HTML.

# Your Site Name

> One-line description of what you do

Brief overview. What problem you solve, who you serve.

## Products

- **Product One**: What it does
- **Product Two**: What it does

## Key Information

- **Website**: https://yoursite.com
- **Pricing**: Freemium

## Links

- [Homepage](https://yoursite.com/)
- [Pricing](https://yoursite.com/pricing)

Notice what is here that robots.txt never contains: your name, what you do, your pricing, your key pages. This is the information an AI assistant repeats when a user asks about your industry.

Side by side

Can robots.txt block AI crawlers?

Yes. You can add a Disallow rule for any AI user-agent and a compliant crawler will respect it. Should you? For most sites, no. Blocking GPTBot or ClaudeBot means the assistant cannot read your content, so it cannot recommend you when someone asks. You take yourself out of the answer.

The reasons to block are specific: paywalled content, proprietary data you do not want in a training set, or server-load concerns. If none of those apply, leaving AI crawlers allowed is the choice that helps you get cited.

Does llms.txt replace robots.txt?

No. They do not overlap. robots.txt still handles access for every crawler, including search bots that never read llms.txt. If you delete robots.txt, you lose access control and your sitemap reference. If you skip llms.txt, AI assistants fall back to guessing your purpose from scattered page content. Each file does a job the other cannot.

The recommended setup

Use both, and make them work together.

• In robots.txt, explicitly allow the AI crawlers you want (GPTBot, ClaudeBot, PerplexityBot, GoogleOther) and reference your sitemap.xml.
• Add a clear, factual llms.txt at your root that describes what you do, your pricing, and your most important pages.
• Keep both at the site root. Neither file works from a subdirectory.
• Keep llms.txt current. AI assistants cite what they find, so a stale summary produces stale answers.