Supabase and Firebase both promise "a backend without running a backend". They get there in very different ways, and picking the wrong one is expensive to undo.

The 30-second version:

The real difference: the data model

Supabase runs on Postgres , a relational SQL database. If your data has clear relationships (users, orders, line items), you get joins, constraints and SQL you already know.

Firebase uses Firestore , a NoSQL document database. It suits flexible, denormalised structures and shines when the shape of your data changes often.

Real-time and mobile

This is Firebase's home turf. Real-time sync is one of its original core strengths and is highly mature, and its native iOS and Android SDKs are deep. Supabase's real-time is functional but less established. If you're building a mobile-first app that lives on live data, Firebase still has the edge.

Lock-in and exit paths

Supabase is open source and can be self-hosted, so you have a way out if pricing or policy changes.…