Supabase vs Firebase: Which Should You Choose?

If you're starting a new project and need a backend, you've probably come across both Firebase and Supabase. Firebase has been around since 2011 and has become synonymous with "backend-as-a-service." Supabase launched in 2020 and has grown rapidly by positioning itself as "the open source Firebase alternative."

But calling Supabase a Firebase alternative undersells how different these platforms actually are. They're built on fundamentally different philosophies about how data should be stored and accessed. Choosing between them isn't about which is "better." It's about which approach fits your project.

I've built production applications with both. Here's what I've learned.

What is Firebase?

Firebase started as a real-time database company in 2011 and was acquired by Google in 2014. Since then, it's grown into a comprehensive platform with over a dozen services: authentication, hosting, cloud functions, analytics, crashlytics, remote config, and more.

At its core, Firebase is built around Firestore, a NoSQL document database. Your data lives in collections of JSON-like documents. There's no fixed schema; documents in the same collection can have completely different fields. This flexibility is powerful for rapid development, but it shapes how you think about your data.

Firebase's killer feature has always been real-time synchronization. When data changes, connected clients update automatically. You don't poll for changes or set up WebSocket connections. It just works. This made Firebase the default choice for chat apps, collaborative tools, and anything requiring live updates.

Google has invested heavily in Firebase's developer experience, particularly for mobile. The Flutter integration is excellent, and the iOS and Android SDKs are mature and well-documented. If you're building a mobile app, Firebase feels like it was designed specifically for you.

What is Supabase?

Supabase takes a different approach. Instead of building a proprietary database, they wrapped PostgreSQL, the most popular open-source relational database, and added the services developers need: authentication, storage, edge functions, and auto-generated APIs.

This means your data lives in tables with defined schemas, foreign keys, and all the relational database features that have been refined over decades. You query with SQL. You get transactions, joins, and constraints that enforce data integrity.

Supabase launched on Hacker News in 2020 and struck a nerve. Developers frustrated with Firestore's limitations, particularly the lack of joins and unpredictable pricing, saw PostgreSQL as a more solid foundation. The project grew quickly, raising significant funding and building a passionate community.

What makes Supabase interesting isn't just that it uses PostgreSQL. It's that they've made PostgreSQL accessible to developers who might otherwise avoid it. The dashboard is clean. The client libraries are well-designed. You can go from zero to a working backend in minutes, but you're not locked into a proprietary system.

The Database Question

This is the decision that matters most. Everything else flows from it.

Firestore stores documents. A user might look like this:

{
  id: "user_123",
  name: "Alice Chen",
  email: "alice@example.com",
  company: {
    name: "Acme Corp",
    role: "Engineer"
  },
  tags: ["premium", "early-adopter"],
  createdAt: Timestamp
}

You can nest data, store arrays, and change the structure anytime. The flexibility is liberating during early development when you're still figuring out your data model.

Supabase stores rows in tables:

CREATE TABLE users (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  name TEXT NOT NULL,
  email TEXT UNIQUE NOT NULL,
  company_id UUID REFERENCES companies(id),
  created_at TIMESTAMPTZ DEFAULT NOW()
);

CREATE TABLE user_tags (
  user_id UUID REFERENCES users(id),
  tag TEXT NOT NULL,
  PRIMARY KEY (user_id, tag)
);

More structure upfront, but the database enforces your rules. That email uniqueness constraint? PostgreSQL won't let you violate it. The foreign key to companies? PostgreSQL ensures you can't reference a company that doesn't exist.

The practical difference shows up when you query related data. In Supabase:

SELECT users.name, companies.name as company_name, array_agg(user_tags.tag) as tags
FROM users
JOIN companies ON users.company_id = companies.id
LEFT JOIN user_tags ON users.id = user_tags.user_id
WHERE users.id = 'user_123'
GROUP BY users.id, companies.id;

One query, all the data you need. In Firestore, you'd make separate queries to users, companies, and user_tags, then stitch the results together in your application code. For simple apps this is fine. For complex apps with lots of relationships, it becomes painful.

Real-Time Capabilities

Firebase's real-time sync is genuinely impressive. You attach a listener, and updates flow automatically:

import { doc, onSnapshot } from 'firebase/firestore';

const unsubscribe = onSnapshot(doc(db, 'rooms', roomId), (snapshot) => {
  const room = snapshot.data();
  updateUI(room);
});

The SDK handles reconnection, offline caching, and conflict resolution. For collaborative applications like real-time editing, multiplayer games, and chat, this is table stakes, and Firebase does it well.

Supabase added real-time later through PostgreSQL's LISTEN/NOTIFY mechanism:

const channel = supabase
  .channel('room-updates')
  .on('postgres_changes', {
    event: '*',
    schema: 'public',
    table: 'rooms',
    filter: `id=eq.${roomId}`
  }, (payload) => {
    updateUI(payload.new);
  })
  .subscribe();

It works, but it's not the same. Firebase's real-time was designed from the ground up; Supabase's is an addition to a database that wasn't built for it. For most applications, Supabase's real-time is sufficient. For applications where real-time is the core feature, Firebase has an edge.

Authentication

Both platforms handle authentication well. You get email/password, OAuth providers (Google, GitHub, Twitter, etc.), magic links, and phone authentication. The flows are similar, the features are comparable.

Firebase has been doing auth longer and supports more OAuth providers out of the box. They also offer anonymous authentication, which is useful for letting users try your app before signing up.

Supabase's auth integrates beautifully with PostgreSQL's row-level security. You can write policies like "users can only see their own data" directly in the database, and they're enforced automatically:

CREATE POLICY "Users see own data" ON user_data
  FOR SELECT USING (auth.uid() = user_id);

This moves authorization logic from your application code into the database, which some developers love and others find awkward. It's powerful when it fits your mental model.

Pricing and Predictability

Firebase's pricing has been a pain point for years. Firestore charges per document read, write, and delete. This sounds reasonable until you realize that a poorly optimized query reading 10,000 documents costs real money, even if you only display 10 results.

Developers have been surprised by Firebase bills that spiked unexpectedly. A viral moment, a bug that triggers excessive reads, or simply underestimating usage can lead to unpleasant invoices. Google has improved the pricing transparency, but the per-operation model remains inherently unpredictable.

Supabase charges for compute and storage, not operations. You pay for database size and the compute resources to run it. This is more predictable. You can estimate costs based on data volume rather than guessing at access patterns.

For small projects, both have generous free tiers. Firebase gives you 50K reads, 20K writes, and 20K deletes per day. Supabase gives you 500MB of database storage and unlimited API requests. At scale, Supabase tends to be cheaper, but your mileage will vary depending on your specific usage patterns.

Vendor Lock-in

This is where philosophy matters.

Firebase is proprietary. Firestore is a Google-only database with no open-source equivalent. If you decide to leave Firebase, you're rewriting your data layer. Your auth users can be exported, but it's not seamless. Cloud Functions are just Google Cloud Functions, which helps, but the core database is locked in.

Supabase is built on open standards. PostgreSQL runs anywhere: AWS, Google Cloud, Azure, DigitalOcean, your own servers. If you outgrow Supabase or want to self-host, you can. Your data, your auth users, your schema: all portable.

For side projects, lock-in doesn't matter much. For businesses, it's worth considering. Being dependent on a single vendor's pricing decisions and feature roadmap is a real risk.

Developer Experience

Firebase's dashboard is feature-rich but can feel overwhelming. There's a lot going on. The Firebase CLI is powerful for deployment and emulation. The local emulator suite lets you run everything offline, which is valuable for development.

Supabase's dashboard is cleaner and more focused. The SQL editor is excellent. You can write and run queries directly in the browser. The table editor feels like a spreadsheet, which makes it approachable for developers who aren't SQL experts.

Both have good client libraries, but they feel different. Firebase's SDK is more opinionated; Supabase's feels closer to working with a regular database. Neither is better. It depends on what you're used to.

When to Choose Firebase

Firebase makes sense when real-time synchronization is central to your application. Chat apps, collaborative editors, live dashboards, and multiplayer games all benefit from Firebase's mature real-time infrastructure.

Mobile development is Firebase's sweet spot. The Flutter SDK is excellent, and the iOS/Android libraries are battle-tested. If you're building a mobile-first app and want to move fast, Firebase gets out of your way.

If your data is genuinely document-shaped (user profiles, content items, configuration), Firestore's flexibility is an asset. Not everything needs to be relational.

And if you're already invested in Google Cloud, Firebase integrates naturally. Cloud Functions, BigQuery, and Google Analytics all work together.

When to Choose Supabase

Supabase makes sense when your data is relational. E-commerce, SaaS applications, and anything with users-orders-products relationships fit naturally into PostgreSQL's model.

If you value open source and portability, Supabase wins decisively. PostgreSQL is a standard. Your skills transfer, your data is portable, and you're not locked into a single vendor.

For complex queries and reporting, SQL is hard to beat. Aggregations, joins, window functions, and CTEs are all areas where PostgreSQL's query capabilities far exceed what Firestore offers.

And if you want a complete backend but also want to understand what's happening under the hood, Supabase is more transparent. It's PostgreSQL with a nice wrapper, not a black box.

The Bottom Line

Firebase and Supabase are both excellent platforms, but they're not interchangeable. Firebase is optimized for real-time, mobile-first, document-oriented applications. Supabase is optimized for relational data, complex queries, and long-term portability.

If you're building a chat app or a mobile game, Firebase is probably the right choice. If you're building a SaaS product or an e-commerce platform, Supabase is probably the right choice. If you're building something in between, think carefully about your data model and pick the database that fits.

The "open source Firebase alternative" framing is good marketing, but it obscures the real decision: do you want a document database or a relational database? Answer that question, and the choice becomes clearer.