Should I use PostgreSQL or Firebase for a web app backend?

Short answer: use PostgreSQL if you want a real backend database you can grow with; use Firebase if you want to move very fast on a simple app and are okay with its constraints.

Choose PostgreSQL if:

• You need relational data: users, orders, comments, permissions, etc.
• You want strong consistency and complex queries/joins.
• You expect to scale features over time.
• You want less vendor lock-in.
• You may use a backend framework like Node, Python, Go, Ruby, Django, Rails, NestJS, FastAPI, etc.

Choose Firebase if:

• You want to build an MVP quickly.
• Your app is mostly real-time or simple document-based data.
• You want built-in services like:
  • authentication
  • realtime sync
  • file storage
  • push notifications
• You’re fine with NoSQL limitations and some lock-in.

A practical rule:

• Web app with business logic, reporting, admin dashboards, payments, or complex relationships → PostgreSQL
• Chat app, collaborative app, prototype, or mobile/web app needing realtime sync fast → Firebase

My default recommendation:

If you’re unsure, start with PostgreSQL.

It’s usually the better long-term foundation, and you can still add:

• auth (Clerk, Auth0, Supabase Auth, or your own)
• realtime features (websockets, Redis, Supabase Realtime, etc.)
• object storage (S3, Cloudflare R2, GCS)

If you want, I can also give you:

1. a decision matrix,
2. a recommendation based on your app type, or
3. compare PostgreSQL vs Firebase vs Supabase.