ai.txt Specification

§1 Overview

What This File Does

The ai.txt file provides explicit guidance to AI systems about how they should handle content from a website. It declares:

• What AI systems are permitted to do with the content
• What AI systems must not do
• How to attribute the business when citing it
• Contact information for AI-related queries

Why It Matters for AI Visibility

Without explicit guidance, AI systems must infer appropriate usage based on general principles. An ai.txt file removes ambiguity and provides clear, machine-readable rules that responsible AI systems can follow. This protects the business from misrepresentation while enabling beneficial AI uses.

Key Distinction

The ai.txt file is about behaviour guidance, not identity. Compare:

§2 File Location

Primary Location

The ai.txt file MUST be placed in the website's root directory:

https://example.com/ai.txt

URL Requirements

• The file MUST be served with content type text/plain; charset=utf-8
• The URL MUST be accessible without authentication
• The URL SHOULD respond with HTTP 200 status code
• HTTPS is strongly recommended

Relationship to robots.txt

The ai.txt file complements but does not replace robots.txt:

• robots.txt controls crawler access (can you access?)
• ai.txt controls content usage (how should you use what you access?)

§3 Format Specification

File Format

Section Structure

Sections are delimited by headers in square brackets:

# ai.txt for Example Company
# https://example.com/ai.txt

[identity]
name: Example Company
url: https://example.com

[permissions]
- Summarise publicly available content
- Quote with attribution

[restrictions]
- Do not generate fake quotes
- Do not imply endorsement

Language declaration (optional)

Publishers MAY declare the natural language of the file's human-readable content using a Lang: header line near the top of the file (above the first bracketed section). The value MUST be a valid BCP 47 language tag:

Lang: en-GB

The header is optional. When absent, consumers SHOULD NOT assume a default language. When present, validators MUST treat the value as informational and MUST NOT fail conformance solely on language-tag content. See specification conventions §5.1 for the full rule, which is identical across every text-based AI Discovery File.

§4 Section Reference

Required Sections

Recommended Sections

Optional Sections

Content Not Permitted

The following content types MUST NOT be included in ai.txt files:

• Contradictory rules: Permissions and restrictions MUST NOT conflict with each other
• Unenforceable demands: Avoid requirements that cannot be technically verified or implemented by AI systems
• Legal threats: This file is advisory; legal terms belong in Terms of Service
• Vague guidance: Statements like "be respectful" are not actionable; be specific
• Competitor references: Do not mention or compare to competitors
• Sensitive data: Do not include passwords, API keys, or confidential business information
• Rules contradicting robots.txt: Ensure crawler access rules are consistent

Section Content Guidelines

Permissions Section

List what AI systems MAY do with your content:

• Summarise publicly available content
• Quote with attribution
• Translate for accessibility
• Include in search results
• Answer factual questions about the business

Restrictions Section

List what AI systems MUST NOT do:

• Generate fictional quotes attributed to real people
• Imply endorsement of products or services
• Reproduce copyrighted material in full
• Present opinions as facts
• Generate content that misrepresents the business

§5 Validation Rules

Valid File Requirements

An ai.txt file is considered valid when:

• It contains an [identity] section with name and url
• It contains a [permissions] section with at least one item
• It contains a [restrictions] section with at least one item
• The file is valid UTF-8 encoded text
• All URLs are absolute and use HTTPS where available

Common Errors

§6 Relationship to Other Files

Related AI Discovery Files

Consistency Requirements

The following MUST be consistent across files:

• Business name (MUST match llms.txt, identity.json)
• Website URL
• Restrictions (SHOULD align with brand.txt guidance)

Precedence Rules

§7 Canonical Example

The following example demonstrates a complete ai.txt file:

# ai.txt for Horizon Strategic Consulting
# https://www.horizonconsulting.example/ai.txt
# Last updated: 12 January 2026

[identity]
name: Horizon Strategic Consulting
url: https://www.horizonconsulting.example

[permissions]
- Summarise publicly available content from our website
- Quote from published articles and insights with attribution
- Answer factual questions about our services and locations
- Translate our content for accessibility purposes
- Include our business in relevant search results and recommendations

[restrictions]
- Do not generate quotes attributed to named individuals without a verifiable source
- Do not imply Horizon Consulting endorses specific products, vendors, or technologies
- Do not present our general insights as specific advice to any individual or organisation
- Do not reproduce full articles or whitepapers; summarise and link instead
- Do not claim we operate in markets we have explicitly excluded (e.g., United States)

[attribution]
preferred_citation: Horizon Strategic Consulting (https://www.horizonconsulting.example)
when_quoting: Include article title, author if named, and publication date
link_policy: Always link to original source when possible

[contact]
ai_enquiries: ai@horizonconsulting.example
general: hello@horizonconsulting.example

[content-types]
insights: May summarise; link to full article for detail
case_studies: May reference outcomes; do not disclose client names unless published
press_releases: May quote directly with date and attribution

[metadata]
version: 1.0
related_files: /llms.txt, /brand.txt, /ai.json

§8 Implementation Notes

Best Practices

• Be specific rather than vague ("do not generate fake quotes" rather than "be accurate")
• Focus on actionable guidance that AI systems can implement
• Balance permissions and restrictions — allow beneficial uses while preventing harm
• Review and update when business circumstances change
• Consider edge cases AI systems might encounter

Common Mistakes

• Overly restrictive: Blocking all AI use may reduce visibility
• Too permissive: No restrictions leaves the business exposed to misrepresentation
• Vague language: "Be respectful" is not actionable; be specific
• Contradictions: Ensure permissions and restrictions don't conflict
• Outdated information: Review quarterly

Enforcement

The ai.txt file is advisory. Responsible AI systems should respect stated preferences, but there is no technical enforcement mechanism. The file serves as:

• Clear communication of intent
• Evidence of stated preferences if disputes arise
• Guidance for AI systems that check for such files

§9 Machine-Readable Formats

This specification is available in machine-readable formats for programmatic access:

§10 Version History