A practical, step-by-step technical SEO checklist for Next.js App Router sites, covering crawlability (robots.ts, sitemap.ts), metadata and canonical URLs, JSON-LD structured data, Open Graph, Core Web Vitals fixes with next/image and next/font, mobile-friendliness, and content quality. Also covers why the same fundamentals matter for AI search visibility. Published on DevStacked, my developer blog covering practical Next.js and SaaS implementation guides.