---
id: "specification-website"
title: "The Website Specification"
creator: "Joost de Valk"
creator_url: "https://joost.blog"
url: "https://specification.website/"
level: "intermediate"
level_max: "advanced"
category: "ai-search-visibility-seo-geo-aeo"
subcategory: "llms-txt-and-agent-readable-sites"
region: "West"
access: "free"
date_added: "2026-10-19"
resource_kind: "learning_resource"
verification_basis: "supplier-inventory-v2.4"
access_evidence: "Supplier-approved free inventory; not independently verified by this site."
domain_top: "AI search visibility (SEO/GEO/AEO)"
domain_sub: "llms.txt and agent-readable sites"
source_type: "guide"
last_verified: "2026-10-19"
last_content_modified: "2026-10-19"
---

[Home](/index.md) · [AI search visibility (SEO/GEO/AEO)](/ai-search-visibility-seo-geo-aeo/index.md) · [llms.txt and agent-readable sites](/ai-search-visibility-seo-geo-aeo/llms-txt-and-agent-readable-sites/index.md)

# The Website Specification

Joost de Valk's sourced reference of web standards from HTML head tags to robots.txt, llms.txt and security.txt, also queryable through an MCP server.

For intermediate–advanced readers. A guide from Joost de Valk; catalog added 2026-10-19, last verified 2026-10-19.

by [Joost de Valk](https://joost.blog)

[Read the original →](https://specification.website/)

Level: [Intermediate–Advanced](/levels/index.md)
Category: [AI search visibility (SEO/GEO/AEO)](/ai-search-visibility-seo-geo-aeo/index.md)
Tags: [ai-search-visibility-seo-geo-aeo](/tags/ai-search-visibility-seo-geo-aeo/index.md), [llms-txt-and-agent-readable-sites](/tags/llms-txt-and-agent-readable-sites/index.md)
Added: 2026-10-19
Last verified: 2026-10-19
Status: ok
Resource kind: learning_resource
Type: guide
Region: West
Original language: en
Access: free
Last modified: 2026-10-19
Subcategory: [llms.txt and agent-readable sites](/ai-search-visibility-seo-geo-aeo/llms-txt-and-agent-readable-sites/index.md)
Verification basis: Supplier-reported import check. Subsequent source corrections and content reviews are recorded separately.
Access evidence: Supplier-approved free inventory; not independently verified by this site.
Source domain: AI search visibility (SEO/GEO/AEO)
Source subdomain: llms.txt and agent-readable sites

Summary in our own words. Rights remain with the original creator. [Credit and correction policy](/about/index.md#credit-policy).

[Plain-text Markdown copy](/e/specification-website/index.md)