robots.txt vs llms.txt: Key Differences Explained

TL;DR: robots.txt vs llms.txt

robots.txt is a standard file that tells traditional search engine crawlers (like Googlebot) which URLs they can or cannot access. llms.txt is a new proposed standard that provides AI language models (like ChatGPT, Claude) with a curated set of URLs to read and learn from, while optionally blocking others. Use both to control how your site is crawled by different types of bots.

What Is robots.txt?

robots.txt is a text file placed at the root of a website (e.g., https://example.com/robots.txt) that communicates with web crawlers using the Robots Exclusion Protocol. It instructs crawlers which parts of the site should not be accessed or indexed.

Example robots.txt

User-agent: *
Disallow: /admin/
Disallow: /private/
Allow: /public/

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

In this example, all crawlers are blocked from /admin/ and /private/ but allowed to crawl /public/. The sitemap location is also provided.

What Is llms.txt?

llms.txt is a newer, unofficial file proposed by the developer community (notably inspired by the llmstxt project) that specifically targets large language models (LLMs) used by AI tools. Its purpose is to provide a clear, machine-readable list of URLs that AI models should use for training or inference, while optionally excluding others.

Example llms.txt

# llms.txt for example.com
# This file helps AI models access the most relevant content.

# Essential pages for AI
https://example.com/about
https://example.com/docs
https://example.com/blog

# Optional: block specific paths from AI crawlers
Disallow: /api/
Disallow: /private/

robots.txt vs llms.txt: Key Differences

| Feature | robots.txt | llms.txt |

|---------|------------|----------|

| Target Audience | Traditional search engine crawlers (Google, Bing, Yandex) | AI language models and their crawlers (GPTBot, Claude, Perplexity) |

| Standard | Official, widely adopted since 1994 | Unofficial, emerging community standard |

| Purpose | Control crawling and indexing for SEO | Curate content for AI training and inference |

| Format | Simple directives (User-agent, Disallow, Allow) | Markdown-like list of URLs with optional directives |

| Enforcement | Voluntary, but most crawlers respect it | Voluntary, and only newer AI crawlers may honor it |

| Granularity | Path-level blocking | Can specify individual URLs or paths |

Why the Difference Matters

Understanding the distinction is crucial because traditional search engines and AI models use different crawlers. A robots.txt file may not be fully respected by AI crawlers, and an llms.txt file is ignored by Googlebot. To fully control access, you need both.

Concrete Example: Blocking AI Crawlers

Suppose you want to block all AI crawlers from your entire site but allow Googlebot. You could add this to your robots.txt:

User-agent: GPTBot
Disallow: /

User-agent: Claude-Web
Disallow: /

User-agent: Googlebot
Allow: /

But this may not work because not all AI crawlers identify themselves. An llms.txt file can explicitly list the URLs you want AI models to access, making it clear:

# llms.txt
https://example.com/public-content
# Do not use any other pages

How to Implement Both Files

Step 1: Create robots.txt

Place at the root of your domain. Include:

User-agent: *
Disallow: /admin/
Disallow: /private/
Disallow: /api/

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

Step 2: Create llms.txt

Place at the root as well. Use a simple list of URLs you want AI models to access. Optionally add Disallow lines for paths to block.

# llms.txt for example.com
https://example.com/about
https://example.com/blog
https://example.com/docs

Disallow: /private/
Disallow: /api/

Step 3: Test Both Files

Use tools like Google Search Console's robots.txt tester and AI-specific crawler simulators to verify your files are correct.

Common Questions About robots.txt vs llms.txt

Do I need both files?

Yes, if you want to control access for both traditional search engines and AI models. robots.txt covers standard crawlers; llms.txt covers AI-specific ones.

Can llms.txt override robots.txt?

No. They operate independently. An AI crawler may check both; if both deny access, it should respect the stricter rule. However, llms.txt is not yet widely supported.

Will Google use llms.txt?

Google has not adopted llms.txt officially. Googlebot still follows robots.txt. However, Google's own AI models may eventually consider llms.txt.

FAQ

What is the main difference between robots.txt and llms.txt?

robots.txt controls traditional search engine crawlers (Googlebot, Bingbot) while llms.txt controls AI language model crawlers (GPTBot, Claude). Both are text files placed at the website root, but they target different bots and have different formats.

Should I use robots.txt or llms.txt to block AI crawlers?

Use both for maximum coverage. robots.txt can block known AI crawler user agents, but not all AI crawlers identify themselves. llms.txt provides a clearer signal for AI models that support it. For complete control, implement both.

How do I create an llms.txt file?

Create a plain text file named llms.txt and place it at the root of your domain (e.g., https://example.com/llms.txt). List the URLs you want AI models to access, one per line. Optionally, add Disallow: lines to block specific paths. Example:

https://example.com/about
https://example.com/blog
Disallow: /private/