The Website Specification Skip to main content Website Spec What a good website does. All topics Checklist MCP About Contribute Search ⌘K All topics Checklist Search MCP server About Contribute GitHub Categories Foundations SEO Accessibility Security Well-Known URIs Agent Readiness Performance Privacy Resilience Internationalisation Foundations SEO Accessibility Security Well-Known URIs Agent Readiness Performance Privacy Resilience Internationalisation
What a good website does.

A platform-agnostic specification of the technical features every
decent website should have — from <title>
to /.well-known/security.txt,
from WCAG contrast to llms.txt.
Written for humans and agents.

Browse all 128 topics →

Get the checklist

★ on GitHub
Categories Ten areas, mapped to widely-accepted standards. All topics → Foundations 14 The HTML, head, and document basics every page needs. SEO 13 Search visibility — robots.txt, sitemaps, canonicals, structured data. Accessibility 20 WCAG-aligned rules so people of all abilities can use the site. Security 12 Headers, transport, and policies that keep visitors safe. Well-Known URIs 9 Standard, agreed-upon paths under /.well-known/. Agent Readiness 18 Things that make a site legible to AI agents and crawlers. Performance 19 Core Web Vitals, caching, images, fonts, network behaviour. Privacy 6 Consent, signals, and respecting visitor choice. Resilience 5 Graceful failure — error pages, offline, redirects. Internationalisation 12 Language, locale, direction, and translated content. Standards, not opinions Each topic links back to the source standard — WHATWG, W3C, IETF RFCs, WCAG, MDN, and the organisations defining the modern web. Platform agnostic Whether you ship WordPress, Drupal, TYPO3, Next.js, Astro, Hugo, a Django app, or plain HTML, the spec is the spec. Implementation hints follow it, not the other way round. Built in the open Every page has an Edit on GitHub link. PRs welcome. Sources credited on every page. Let your agent query the spec.
The whole spec is available as an open MCP server — read-only, no auth — plus a published Agent Skill that teaches any compatible agent when and how to use it. Per-page Markdown is available via /llms.txt and Accept: text/markdown on any spec URL.
Connect MCP → Agent Skill llms.txt Agent-readiness spec → {
"mcpServers": {
"specification-website": {
"transport": "http",
"url": "https://mcp.specification.website/mcp"
}
}
} How to use this site 01 Audit Run through the checklist. Each item is a “does the site do this — yes or no.” 02 Learn Click into any item for what it is, why it matters, and how to implement it. 03 Improve Found a gap, a stale fact, or a missing topic? Open a PR. Sources required. The Website Specification A platform-agnostic, full specification of the technical features a good website should have. Built in the open under an MIT licence.
Built in the open. Contribute on GitHub → Topics FoundationsSEOAccessibilitySecurityWell-Known URIs More Agent ReadinessPerformancePrivacyResilienceInternationalisation Project About Contribute Checklist Privacy llms.txt MCP server security.txt RSS
© 2026 Joost de Valk and contributors. Content licensed under
CC BY 4.0; code under
MIT.

This site is itself a worked example of the spec. See how → Search esc close ↑ ↓ navigate ↵ open

The Website Specification is presented as a platform-agnostic specification detailing the technical features that every competent website ought to possess, covering aspects ranging from fundamental HTML elements like the title to established security protocols such as /.well-known/security.txt, and covering accessibility standards like WCAG contrast, extending to modern concerns such as llms.txt. It is designed to be applicable to both human understanding and agent interaction.

The specification is organized into ten core categories which are mapped to widely accepted standards. These categories include Foundations, SEO, Accessibility, Security, Well-Known URIs, Agent Readiness, Performance, Privacy, Resilience, and Internationalisation. Each topic is grounded in established standards, linking directly back to authoritative sources such as WHATWG, W3C, IETF RFCs, WCAG, MDN, and the organizations that define the modern web, emphasizing that the content relies on standards rather than subjective opinions.

A key feature of the specification is its platform agnosticism; it serves as the definitive standard regardless of the underlying technology used for implementation, whether the developer chooses WordPress, Next.js, plain HTML, or any other framework. Implementation guidance is provided separately, adhering to the specification rather than dictating it.

The specification is built with an open philosophy, available under an MIT license and hosted on GitHub, which encourages community contribution through pull requests and ensures that sources are credited on every page. It functions as an open MCP server that allows agents to query the specification, and it features a published Agent Skill that teaches compatible agents how to utilize the specification. Additionally, page-specific Markdown is accessible via /llms.txt, which accepts text/markdown content from any specification URL.

Users can interact with the specification through a structured process: auditing the content by running through the checklist to determine current compliance, clicking on specific items to understand their necessity, and proposing improvements by opening pull requests when gaps or missing information are identified, requiring source justification. The availability of the specification facilitates a structured approach to ensuring that websites meet high technical standards across these interconnected domains.