What Is llms.txt and How to Use It on Your Website

As AI-powered search engines and chatbots increasingly become the way people discover businesses online, a new emerging standard called llms.txt gives website owners direct control over how AI understands their content. Think of it as a robots.txt file — but built specifically for large language models like ChatGPT, Claude, Gemini, and Perplexity.

What Is llms.txt?

An llms.txt file is a plain Markdown-formatted text file served at /llms.txt on your website’s root domain. Rather than forcing AI crawlers to wade through cluttered HTML, JavaScript, and adverts to figure out what your site is about, the file gives them a clean, structured summary of your most important pages and content.

The core idea is simple: instead of AI guessing which pages on your site are most relevant, you tell it directly. This is particularly powerful for Answer Engine Optimisation (AEO) — the practice of getting AI tools to surface your website when users ask relevant questions.

How It Differs from robots.txt and sitemap.xml

These three files serve very different purposes for very different audiences. While robots.txt tells crawlers what not to visit and sitemap.xml lists everything, llms.txt is a curated, hand-picked guide to the most valuable content on your site. It’s quality over quantity — and that’s exactly what AI tools need to generate accurate answers about your business.

• robots.txt — Controls crawler access | Custom syntax | For search engine bots
• sitemap.xml — Lists all URLs for indexing | XML format | For search engine bots
• llms.txt — Curates key content for AI | Markdown format | For LLMs and AI agents

The llms.txt File Format

The file uses standard Markdown and follows a consistent structure. The required elements are an # H1 title (your website or brand name) and a > blockquote (a one-sentence description of your site’s purpose). You can then add optional section headings and links to your most important pages with a brief description of each.

You can also create additional variants:

• llms-full.txt — A single file containing all your site’s content compiled into Markdown, useful for pasting directly into an AI tool as full context.
• .md page variants — Individual pages served with .md appended to the URL (e.g., yoursite.com/about.md) for AI-friendly Markdown versions of each page.

Why It Matters for SEO and AEO

When someone asks ChatGPT or Perplexity about web design services in your area, AI tools that have indexed or visited your site will produce a more accurate, confident response about your business if an llms.txt file is present. The file eliminates ambiguity by explicitly pointing AI to your best pages, services, and resources.

As AI-driven search continues to grow, having llms.txt in place is a low-effort, high-value step for future-proofing your online visibility. It works alongside your existing SEO strategy — not instead of it.

Tutorial: Creating Your llms.txt File

Step 1 — Plan Your Key Pages

Before writing anything, list the most important pages on your site. Focus on pages that explain what you do, demonstrate your authority, or would best answer a customer’s question. For a web design agency, this might include your homepage, services page, portfolio, blog, and contact page.

Step 2 — Write the File

Open a plain text editor (VS Code, Notepad++, or TextEdit on Mac) and structure your file like this:

# Your Business Name > A one-sentence description of what your business does and who it serves. A short paragraph giving a bit more context about your services and location.

## Services - [Service One](https://yourwebsite.com/service-one): Brief description of this service.

- [Service Two](https://yourwebsite.com/service-two): Brief description of this service.

- [Service Three](https://yourwebsite.com/service-three): Brief description of this service.

## Portfolio - [Our Work](https://yourwebsite.com/portfolio): Examples of completed projects.

## Blog - [Blog](https://yourwebsite.com/blog): Tips, guides, and industry insights. ## Contact

- [Get in Touch](https://yourwebsite.com/contact): Request a quote or discuss your project.

Step 3 — Save the File Correctly

Save the file as exactly llms.txt with UTF-8 encoding. On Windows, double-check it hasn’t saved as llms.txt.txt — a very common mistake. On Mac, go to Format > Make Plain Text in TextEdit before saving.

Step 4 — Upload to Your Root Directory

Upload the file to the root directory of your website — the same folder where your robots.txt lives. You can do this via:

• FTP (FileZilla or similar) — upload to public_html/
• cPanel File Manager — navigate to root and upload directly
• WordPress — use SFTP or a plugin like WP File Manager

Once uploaded, it must be publicly accessible at https://yourdomain.com/llms.txt.

Step 5 — Test and Use It

Visit your URL in a browser to confirm the file loads correctly. Most AI models don’t yet automatically discover llms.txt files on their own, so you can actively use it by:

• Sharing the direct URL with an AI tool (e.g., “Here is my site: https://yourdomain.com/llms.txt — what services do I offer?”)
• Copying and pasting the file contents into your AI prompt as context
• Uploading the file directly to AI tools that support file uploads

Optional — Use a Generator

If you’d rather automate the process, tools like Firecrawl (llmstxt.firecrawl.dev) can crawl your website and auto-generate both llms.txt and llms-full.txt for you. Simply enter your URL, click generate, and download the files ready to upload.

Keeping It Updated

Your llms.txt file should be treated like a living document. Whenever you add new key pages, launch new services, or update your main content areas, update the file to reflect those changes. A stale llms.txt pointing to old pages or outdated descriptions could mislead AI tools