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Glossary · web

SSR (Server-Side Rendering)

Definition

SSR (Server-Side Rendering) renders HTML on the server instead of the browser. The user receives ready HTML — faster LCP, better SEO, smaller JS bundle. Next.js, Remix, Nuxt make SSR the default.

Published: 2026-05-05Updated: 2026-05-05

Detailed explanation

Traditional SPA (CSR) ships empty HTML + JS to the browser; JS then draws UI — slow first paint + weak SEO. With SSR, the server prepares HTML and sends it; the browser starts rendering immediately (FCP <500ms).

4 approaches: SSR (per-request server render), SSG (build-time static HTML), ISR (Incremental Static — periodic re-render), CSR (browser-only). Next.js App Router supports all in 2026; SSR is default.

Pros: fast LCP (<1.5s achievable), SEO-friendly (Google bot reads HTML), small JS bundle. Cons: server cost (compute per request), TTFB slightly higher (~200-500ms).

Use cases

E-commerce product pages (SEO + speed critical)

Blog + content sites

Brand vitrines + landing pages

Personalized dashboards (user-specific SSR)

Pros

  • +Fast LCP / FCP (<1.5s)
  • +SEO-friendly (Google bot sees HTML)
  • +Small JS bundle (30-50% smaller with RSC)
  • +Edge runtime for global speed

Cons

  • Server cost (compute per request)
  • TTFB ~200-500ms (CSR 50ms)
  • Caching strategy more complex
  • Overkill for highly interactive apps (SPA better)

Related terms

CSRSSGISRHydrationRSC

Related services

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