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Technical SEO for Modern Sites: A 2026 Checklist

Indexation, Core Web Vitals budgets, hreflang, and JSON-LD patterns for headless multilingual sites. A developer-friendly SEO checklist for 2026.

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1 min readAndrew Green · Lead Developer

Technical SEO is the foundation every content strategy sits on. When rendering, routing, or locale setup is wrong, even great articles never rank.

Indexation hygiene

One canonical URL per locale, consistent trailing slashes, and sitemaps that mirror published content — not staging routes. Block low-value faceted URLs early.

Performance as a ranking signal

Budget LCP, INP, and CLS in CI. Lazy-load below-the-fold media, serve AVIF/WebP variants, and avoid layout shift from cookie banners or web fonts.

Structured data & hreflang

Article and Organization schema should match visible content. Hreflang pairs need reciprocal links and x-default; machine-readable llms.txt helps discovery tools.

Key takeaways

  • One canonical URL per locale keeps indexation clean.
  • Budget Core Web Vitals in CI, not only after launch.
  • JSON-LD and hreflang must match visible content and reciprocal locales.

Related

    Technical SEO Checklist 2026 | LULA-SOFT