HTML Best-Practice and Metadata Signals of Popular Websites (2026)

A reproducible point-in-time dataset (2026-07-20) of eight HTML best-practice and metadata signals (UTF-8 charset, html lang attribute, responsive viewport, Open Graph, Twitter Card, JSON-LD structured data, canonical link, meta description) on the homepages of 20 widely used websites. Derived from the served homepage HTML with curl; fully reproducible; no fabricated values. Homepage-only and initial-HTML-only, so client-rendered signals may under-report. Compiled by HTML5 Advent. More web-standards guides: html5advent.com.