Astro 6 SSR: The Islands Architecture Finally Makes Sense

For years the frontend world argued about SPA versus MPA as if it were a religious war. Astro's islands model quietly ended the fight: ship HTML by default, hydrate only the interactive slivers.

Per-route rendering

The killer feature is granularity. One flag flips a page from static to server-rendered:

export const prerender = false;

Your marketing pages stay static and cacheable. Your dashboard renders per-request against the database. Same project, same components.

Islands, not oceans

A React editor, a search box, a theme toggle — these become islands of interactivity in a sea of static HTML. Everything else ships zero JavaScript.

• client:load — hydrate immediately
• client:visible — hydrate on scroll
• client:only — skip SSR, render on client

The result: Lighthouse scores that make your PM cry happy tears.