Technical SEO for Next.js: Complete 2025 Checklist

This checklist covers the most important elements of technical SEO in Next.js App Router. Apply it before publication and in periodic audits.

Core Web Vitals (CWV)

Core Web Vitals are key metrics that Google uses to assess site quality. LCP (Largest Contentful Paint) should be below 2.5 seconds – achieve this through priority for hero image, preconnect to CDN, and preload fonts. INP (Interaction to Next Paint) must be below 200ms, requiring removal of unnecessary JavaScript, avoiding heavy effects, and using passive events. CLS (Cumulative Layout Shift) should be below 0.1 – reserve space for media and avoid dynamic element shifts.

Metadata and Sitemap

Proper metadata is the foundation of SEO. Use generateMetadata per page, ensuring unique titles and descriptions and correct canonical URLs. robots.ts and sitemap.xml should be automatic and current for blog and offers. Don't forget OpenGraph/Twitter meta and OG images, which can be generated automatically or static.

Hx Structure and Content

Header structure is key to good SEO. Use one H1 per page, and H2/H3 as logical sections. Keyword should appear in H1, title, and first 100–150 characters of content. Don't forget internal linking to key offers and related articles – this helps Google understand your site structure and passes authority between pages.

Schema.org (Structured Data)

Structured data helps Google better understand your site content. Use Article, BreadcrumbList, FAQPage where appropriate, and Organization globally. For offers, add Product/Service with price and AggregateRating for reviews – this can result in rich snippets in search results.

i18n and hreflang

For multilingual sites, alternate tags with hreflang for languages/markets and correct x-default are crucial. Ensure consistent slugs, meta and content translations, avoiding duplication – this helps Google properly index different language versions.

Performance and Bundling

Performance is key to good SEO. Use code-splitting and dynamic() for heavy components, avoiding hydration of heavy libraries on critical views. Optimize images with next/image, WebP/AVIF, and lazy-loading outside viewport – this significantly improves Core Web Vitals.

Caching and ISR

Smart caching is the foundation of performance. Use ISR (revalidate) for blog and edge cache where it makes sense. Cache tags for fetch and stale-while-revalidate in appropriate places ensure fast loading while maintaining content freshness.

Security and Crawlability

Security is the foundation of Google trust. Set appropriate headers: CSP, HSTS, X-Frame-Options, X-Content-Type-Options. Ensure 404/410 for outdated addresses and 301 for permanent changes – this helps Google properly index your site.

Analytics and Monitoring

Monitoring is key to continuous SEO improvement. Use PostHog/GTM to track conversion events and scroll, having a clear measurement plan. Search Console, sitemap ping, and position monitoring and CWV in CrUX help you track progress and identify areas for improvement.