Rendering Strategies (CSR / SSR / SSG / ISR / RSC)

How and where a page’s HTML is produced — client-side, server-side, at build time, incrementally, or via server components — a decision that is simultaneously a performance and a crawlability choice.

Definition

The rendering strategy determines whether the browser receives complete HTML or an empty shell it must hydrate. Options span CSR (client-side, JS builds the page), SSR (server renders per request), SSG (pre-rendered at build), ISR (incremental static regeneration), and RSC (server components + minimal client JS). Per Web Development Best Practices 2026: Engineering Guide, 2026 best practice is server-first (SSR/SSG/ISR/RSC), with pure CSR reserved for non-indexable pages.

This is a canonical both-pillar decision: it drives Core Web Vitals (bundle size, LCP/INP) and crawlability/indexing (Technical SEO from Architecture). CSR yields an empty shell to Googlebot → delayed indexing and lower rankings; SSR yields complete HTML → 2–4× faster indexing. Established.

Key Properties

• Server-first wins for indexable content (SSR/SSG/ISR/RSC); CSR only for non-indexable/highly-interactive views.
• Performance ↔ SEO coupling: the same choice affects both bundle/vitals and crawl/index speed.
• CSR risk: empty initial HTML → poor LCP/INP, delayed (weeks) indexing.
• Decision drivers: data-display vs. rich client state; indexability; global latency (pairs with edge, see Web Architecture & Scalability).

Examples from Sources

In the Sources

Related

Concepts: React Server Components (RSC), Core Web Vitals, Web Architecture & Scalability, Technical SEO from Architecture Entities: Next.js, React, Vercel