Static Generation

App Router decides whether a page is static, dynamic, or revalidatable based on cache rules.

Static rendering (SSG)

• Automatic when no dynamic params, no no-store, no cookies/headers.
• HTML + RSC payload generated at build time.

ISR

• Background revalidation after a time window.

export const revalidate = 60;

fetch(url, { next: { revalidate: 120 } });

How ISR works

1. User gets cached version.
2. After revalidate, Next.js regenerates in background.
3. New version replaces old.

Static fetch

• fetch() with cache: "force-cache" keeps data static.
• Caches: Data Cache, RSC Cache, Full-Route Cache.

What makes a route dynamic

• cache: "no-store"
• cookies/headers
• dynamic = "force-dynamic"
• dynamic params without pre-generation

Summary

• revalidate = N → ISR
• no dynamics → SSG
• no-store → SSR