Open source alternatives to Firebase

What Firebase does

Firebase groups Google’s app development services into products for building and for running apps. On the backend side, Cloud Firestore is a NoSQL document database with realtime listeners and offline caching on mobile and web, and the older Realtime Database syncs a JSON tree to clients. Firebase Authentication handles sign-in, Security Rules control what each client may read and write, Cloud Functions run code in response to Firebase events and HTTPS requests, and Cloud Storage holds user files. Firebase SQL Connect, renamed from Data Connect, adds a managed PostgreSQL database on Cloud SQL with generated SDKs. Hosting, App Hosting, Cloud Messaging, Crashlytics and Remote Config cover the rest of the app lifecycle, with SDKs for Apple platforms, Android, the web, Flutter, Unity and C++.

Why people look for an alternative

• Only on Google’s infrastructure. There is no self-hosted edition. Locations are set per product and per resource, and Cloud Functions run in us-central1 unless you choose another region.
• Plan requirements. Since changes announced in September 2024, Cloud Storage for Firebase, including default buckets, needs the pay-as-you-go Blaze plan; projects on the no-cost Spark plan lose access to their buckets. Blaze still includes some no-cost usage.
• Getting data out. Firestore’s managed export also requires billing, writes files in LevelDB log format to Cloud Storage and counts one read per exported document. User accounts can be exported with the Firebase CLI, but passwords are hashed with Firebase’s own modified scrypt, so the new system must support those parameters or users have to reset their passwords.
• A model specific to Firebase. Firestore’s nested documents and Security Rules do not map directly onto other databases, and the longer an app grows on them, the more work it takes to leave.
• Discontinued products. Firebase Dynamic Links shut down on 25 August 2025, and links served by it stopped working.

What to compare in an alternative

1. The database. Postgres, SQLite, MongoDB or another store, and how much remodeling your Firestore collections need.
2. Authorization. Row-level security, per-collection rules or ACLs that can replace your Security Rules.
3. Auth providers and user import. The sign-in methods you use and whether Firebase password hashes can be imported.
4. Realtime and offline. Live queries or subscriptions in the client SDKs for your platforms, and whether offline caching matters to you.
5. Functions and triggers. The languages supported and the events that can trigger code.
6. Hosting. An official cloud, or the effort of running it yourself.

Which one to choose

Supabase is the most complete general-purpose replacement: Postgres with auth, auto-generated APIs, realtime, storage and edge functions, plus official tools for moving Firebase Auth users, Firestore data and Storage files. Appwrite covers the widest range of Firebase products, including messaging and hosting, and its console can import Firebase Auth users and top-level Firestore documents. Nhost suits teams that want GraphQL on Postgres, and InsForge is a Postgres backend built to be driven by AI coding agents. For a small backend that is easy to run, PocketBase and TrailBase are single executables with SQLite, but you host them yourself. Parse Server is a mature Node.js backend on MongoDB or PostgreSQL with push notifications and Cloud Code, and Kuzzle fits IoT projects that need MQTT and search. Note that only Supabase and Appwrite offer official Firebase importers; with the others, plan the data move yourself.