Lighthouse 90+ checklist: performance, SEO, accessibility

Build for Core Web Vitals: avoid layout shift, ship minimal JS, and optimize images. Core Web Vitals measure real user experience: Largest Contentful Paint (LCP) for loading performance, Cumulative Layout Shift (CLS) for visual stability, and Interaction to Next Paint (INP) for interactivity.

Use semantic HTML and consistent heading hierarchy. This helps both screen readers and search engines understand your content structure. Use h1 for your main title, h2 for section headings, and h3 for subsections. Avoid skipping levels.

Treat metadata, canonical URLs, and structured data as first-class features. Add Open Graph tags for social sharing, canonical URLs to prevent duplicate content issues, and JSON-LD structured data to help search engines understand your content better.

Implementation checklist: minimize unused CSS/JavaScript, defer non-critical scripts, use next/image for optimized images, implement proper heading hierarchy, add ARIA labels where needed, and include structured data for your content type.