Firebase

Firebase gives you a complete backend-as-a-service: database, authentication, file storage, hosting, and serverless functions — all managed by Google. It's incredibly fast for prototyping, but its proprietary NoSQL database (Firestore), vendor lock-in, and unpredictable pricing at scale push many teams toward open source alternatives.

Supabase is the most direct Firebase alternative — it provides the same developer experience (auth, database, storage, real-time subscriptions, edge functions) but built on PostgreSQL instead of Firestore. This means you get a relational database with SQL queries, joins, foreign keys, and the vast PostgreSQL extension ecosystem. Appwrite offers a similar all-in-one backend with a focus on developer experience and multi-platform SDKs (web, Flutter, React Native, iOS, Android). PocketBase takes a minimalist approach — a single Go binary that gives you a SQLite-based backend with auth, file storage, and real-time subscriptions, perfect for small projects and prototypes.

The database architecture difference is critical. Firestore's document model works well for simple data but becomes painful when your data has relationships (users → teams → projects → tasks). PostgreSQL handles relational data naturally. If you start with Firebase and your data model grows complex, migrating away from Firestore is a significant engineering effort — starting with Supabase or Appwrite avoids this risk entirely.

Cost predictability also matters. Firebase's pay-per-operation pricing can produce surprise bills when traffic spikes. Self-hosted alternatives have fixed infrastructure costs regardless of usage, making budgeting straightforward.