What Is llms.txt? The Complete Guide for 2026

If you've heard people talk about adding an llms.txtfile to their website but aren't sure what it actually is, this guide breaks it down in plain English — what the file contains, why AI models care about it, and how to create one for your own site in under a minute.

What is an llms.txt file?

An llms.txt file is a markdown text file you publish at the root of your domain, served at yourdomain.com/llms.txt. Its job is to give large language models — the engines behind ChatGPT, Claude, and Perplexity — a clean, structured summary of your site: your brand name, a one-line description of what you do, and a curated list of your most important pages with short explanations.

It's the AI-era counterpart to the sitemap. A sitemap helps search crawlers find every URL; an llms.txt file helps an AI model understand what your site is about without wading through navigation menus, cookie banners, and JavaScript.

What does the format look like?

The standard, defined at llmstxt.org, is deliberately simple. A typical file starts with an # heading for your brand, a > blockquote tagline, an optional paragraph of context, and then ##sections (Documentation, Blog, Pricing, and so on) containing markdown links with brief summaries. Because it's just markdown, it's readable by humans and trivially parseable by machines.

Why do AI models use it?

LLMs have limited context windows and often struggle with heavy, script-driven HTML. When a model can't read your site cleanly, it fills the gaps with guesses — which is how inaccurate brand descriptions and missing citations happen. An llms.txt file removes the ambiguity by stating, in a format AI consumes natively, exactly what you want it to know. For more on why this matters, see how to improve your visibility in ChatGPT, Claude & Perplexity.

Isn't this just robots.txt?

No — and the difference matters. robots.txt restricts what crawlers may access; llms.txt highlights what you want AI to read. We cover the full comparison in llms.txt vs robots.txt.

How do I create one?

You can write the file by hand, but the fastest path is to let a generator build it from your live site. Our free llms.txt generator crawls your homepage, extracts your brand and key pages, and produces spec-compliant markdown you can edit and download in about 30 seconds — no account required. Upload the result to your site root and AI tools that support the standard will start using it.