How do you implement server-side rendering with Firebase?

Server-Side Rendering (SSR) with Firebase can be implemented through several approaches: (1) Firebase Hosting + Cloud Functions — use Cloud Functions as the SSR server. Express.js function renders the React/Vue app server-side: the function fetches Firestore data using the Admin SDK (no auth required for server), renders HTML, returns it. Firebase Hosting rewrites route traffic to the function. This is Firebase's native SSR approach; (2) Firebase Hosting + Cloud Run — deploy a Docker container (Next.js, Nuxt.js SSR server) to Cloud Run; Firebase Hosting rewrites to the Cloud Run URL. Preferred for complex SSR apps with long cold starts that benefit from container warming; (3) Next.js + Firebase Framework Hosting — firebase experiments:enable webframeworks enables automatic Next.js deployment to Firebase with SSR detected automatically; API routes → Cloud Functions; SSR pages → dynamic rendering; static pages → CDN. (4) Admin SDK for server-side Firestore — SSR servers must use the Admin SDK (not the client SDK) to bypass Security Rules: const admin = require("firebase-admin"); admin.initializeApp(); const db = admin.firestore(). Use service account credentials for the Admin SDK in Cloud Functions (auto-configured) or Cloud Run (manual service account setup).