How the rendering models differ
Client-side React ships a JS bundle that renders in the browser; crawlers must execute it. Next.js can pre-render on the server (SSR), at build time (SSG), or incrementally (ISR) — delivering HTML that both users and search engines consume instantly.
SEO and performance implications
Server-rendered pages typically show faster LCP and complete metadata on first byte, which helps crawling, social previews, and conversions. The gap matters most for marketing pages, blogs, docs, and product listings.
Cost and complexity trade-offs
SSR needs server or edge compute per request; SSG/ISR is nearly free to serve from a CDN. Dashboards with heavy personalization often stay client-rendered inside an otherwise static Next.js shell — the hybrid pattern we use most.
A practical decision framework
Choose Next.js when SEO, social sharing, or first-load speed drives revenue. Stay with Vite/CRA for internal tools behind login. Migrate when organic traffic plateaus despite good content — rendering is often the bottleneck.
Migration without losing rankings
Freeze URL structures, map every legacy route, implement 1:1 redirects, preserve metadata and structured data, then monitor Search Console coverage and Core Web Vitals for four weeks post-cutover.