How to Create an llms.txt File (Step-by-Step)

Goal

Publish a single Markdown file at https://yourdomain.com/llms.txt that tells AI agents: who you are, what the product does, and which URLs to prefer. This guide walks through a complete first file in about thirty minutes.

Validate any time with the free llms.txt Validator — paste mode or fetch URL.

Step 1 — Decide the audience

Write for a model that has never heard of you. Avoid internal codenames without explanation. Prefer:

• Product name people search for
• One-sentence category (“billing API for Indian SaaS”)
• Who should use the primary docs links

Step 2 — Write the H1 and summary

Create a file named llms.txt locally:

# Northwind API

> Northwind API is a REST platform for inventory and order data used by mid-market retailers.

Rules:

• First non-empty line must be # Title
• Put the elevator pitch in a > blockquote, not a second heading
• Keep the summary scannable (1–3 sentences)

Step 3 — Optional intro paragraph

Still without extra headings, add a short paragraph if agents need grounding:

Prefer official docs over marketplace blog posts. Authentication always uses API keys issued in the dashboard.

Step 4 — Add H2 sections with absolute links

Pick 2–4 section names (Docs, API, Examples, Policies, etc.). Under each, only use list items with Markdown links:

## Docs

- [Quickstart](https://docs.northwind.example/quickstart): Install SDK and first GET
- [Authentication](https://docs.northwind.example/auth): API keys and scopes
- [Rate limits](https://docs.northwind.example/limits): Quotas and headers

## Optional

- [Changelog](https://docs.northwind.example/changelog): Release notes
- [Blog](https://northwind.example/blog): Product stories

Notes after the colon are optional but useful. Put skippable content under ## Optional.

Step 5 — Validate

Open the llms.txt Validator:

1. Paste the full file, or use Fetch URL once it is on staging.
2. Fix every error (missing H1, list items without links, ### headings).
3. Fix warnings when practical (relative URLs, missing summary, huge size).
4. Confirm stats: sections, absolute link count, Optional detected.

Step 6 — Deploy to the root

Copy the file to the web root of your host:

• Static hosts: public/llms.txt or static/llms.txt
• WordPress: often theme root or a plugin that serves root files
• Cloudflare Pages / Netlify / Vercel: include in the published output directory

Ensure it is not blocked in robots.txt. You can still mention the path; just do not Disallow /llms.txt under User-agent: *.

Ideal response headers when you control them:

Content-Type: text/plain; charset=utf-8

Step 7 — Verify live

curl -sS -D- https://yourdomain.com/llms.txt -o /tmp/llms.txt | head

You want HTTP 200 and a body that starts with # . Then run Fetch URL in the validator against your production domain.

Step 8 — Maintain

• Re-check after doc migrations so links do not 404
• Keep size sane; grow long text in llms-full.txt
• Align crawler blocks separately with the robots.txt Generator

Starter template

# Your Product Name

> One or two sentences: what you sell and who it is for.

How agents should use this file: prefer Docs first; treat Optional as background.

## Docs

- [Getting Started](https://example.com/docs/start): First successful setup
- [Core Concepts](https://example.com/docs/concepts): Mental model of the product

## API

- [Reference](https://example.com/docs/api): Endpoints and schemas

## Optional

- [Status](https://status.example.com/): Uptime and incidents
- [Blog](https://example.com/blog): Announcements

Paste this into the validator, swap in your URLs, and publish. For tone, size, and section-naming tips beyond the minimum, continue with llms.txt best practices.