The Website Specification - GitHub Technical Website Checklist by Joost team.

From their Github:

“

What this is

The web is a layer cake of standards: WHATWG defines HTML, W3C ratifies WCAG, the IETF publishes the RFCs behind security headers and /.well-known/ URIs, IANA registers the namespaces, search engines publish their own rules, browsers add quirks. Almost nobody carries the whole picture.

This site collects the slices into one platform-agnostic specification — sources cited on every page.

It is not a framework. It is not a tutorial. It is a spec, in the same way the HTML Living Standard is a spec: outcomes, requirements, references.

What this is not

Not platform-specific. No “use this Next.js plugin” advice — the spec describes the outcome, you choose the implementation. Not opinion. Where there is no settled standard, the spec says so. Not a marketing site. No newsletter capture. No cookies. Aggregate Plausible analytics; that’s it.

Categories

• Foundations — HTML, head, document basics.
• SEO — search visibility.
• Accessibility — WCAG-aligned rules.
• Security — headers, transport, policies.
• Well-Known URIs — agreed paths under /.well-known/.
• Agent Readiness — making a site legible to AI agents.
• Performance — Core Web Vitals, caching, fonts.
• Privacy — consent, signals, respecting choice.
• Resilience — graceful failure.
• Internationalisation — language, locale, direction.”