Standards & Guides📅 2026-08-15• ⏱️ 2 min read• ✍️ SubmitLLMs Team

The Complete Guide to llms.txt & llms-full.txt in 2026

Learn how llms.txt and llms-full.txt allow AI models like ChatGPT, Claude, and Perplexity to ingest and understand your website with zero hallucination.

Introduction to the llms.txt Standard

As Large Language Models (LLMs) like OpenAI ChatGPT, Anthropic Claude, Perplexity, and Google Gemini become the primary interface through which users discover information, products, and services, traditional web indexing is no longer enough.

Standard HTML pages are filled with navigation menus, cookie banners, tracking scripts, and complex CSS stylesheets that consume thousands of tokens without adding informative context.

The llms.txt proposal (introduced via llmstxt.org) solves this by providing a clean, structured Markdown file at the root of your domain: https://yourdomain.com/llms.txt.

What is the Difference Between llms.txt and llms-full.txt?

1. `llms.txt` (Brief Overview & Index)

The primary llms.txt file serves as an executive summary and curated index of your website. It typically includes:

•H1 Title: The name of your product, project, or website.

•Blockquote Summary: A 1–2 sentence description of what the project does.

•Key Sections: Core documentation, API links, pricing overview, and curated markdown URLs.

•Target Token Count: Recommended to keep under 2,000–4,000 tokens for quick inference.

2. `llms-full.txt` (Complete Documentation & Data)

The extended llms-full.txt file contains the full context of your documentation, guides, API endpoints, and schemas bundled into a single readable Markdown document. AI coding assistants (such as Cursor, Windsurf, and Claude Code) use this file to load complete knowledge without making dozens of HTTP round-trips.

Example llms.txt File Format

# SubmitLLMs

> Free AI readiness directory and tools to make your website discoverable by LLMs and AI agents.

## Core Features
- [AI Readiness Scanner](https://submitllms.com/scanner): Audits llms.txt, robots.txt, and agent.json compliance.
- [llms.txt Generator](https://submitllms.com/generator): Generates standard-compliant markdown files automatically.
- [Live Directory](https://submitllms.com/directory): Index of active AI-ready domains with verified quality scores.

## API Documentation
- [Directory API](https://submitllms.com/api/directory): JSON feed of active listings.
- [Badge API](https://submitllms.com/badge): Embeddable SVG AI-readiness verification badges.

How to Test and Validate Your llms.txt

•Host the file at the root of your domain: https://example.com/llms.txt.

•Ensure correct MIME type: Return text/plain or text/markdown with utf-8 charset.

•Run a free scan: Use the SubmitLLMs Scanner to verify token count, link validity, and header structure.

•Submit to the Directory: Submit your domain on SubmitLLMs to get indexed across AI crawlers and developer toolchains.

Want to check your own website's AI readiness?

Scan your domain in seconds to verify compliance with llms.txt, robots.txt, and agent.json protocols.

Run Free AI Scanner →Generate llms.txt