By Mehdi HassanSupabase vs Firebase vs custom Postgres: which should a startup use?
A startup building B2B SaaS should usually use Supabase or a managed Postgres, because its data is relational and SQL keeps reporting, permissions and migrations simple. Firebase is the better fit for mobile-first consumer apps that need offline sync and real-time updates with minimal backend code. Custom Postgres suits teams with backend engineers who want control.
This is one of the decisions in our hub on full-stack product engineering for startups, and it shapes every feature after it. We judge each option on four things: the data model, what's bundled, how it fits a Next.js app, and the cost of leaving.
What's the real difference between Supabase and Firebase?
The real difference is the database. Supabase is built on Postgres, a relational SQL database, with auth, storage, real-time and edge functions around it. Firebase is built mainly on Firestore, a NoSQL document database, with Google's auth, hosting, functions and mobile tooling around it. Everything else follows from that.
Supabase | Firebase | Custom managed Postgres | |
|---|---|---|---|
Database | Postgres (SQL) | Firestore (documents); Postgres via Data Connect | Postgres (SQL) |
Auth | Built in, tied to row-level security | Firebase Auth, strong on mobile | Bring your own provider |
Real-time | Postgres changes and channels | Core strength, with offline sync | Add a service yourself |
Querying | Full SQL, joins, views | Limited joins; denormalize data | Full SQL |
Self-hosting | Open source, self-hostable | No | Yes, by definition |
Exit cost | Low: standard Postgres dump | High: data model rework | Lowest |
Ops work | Low | Lowest | Highest |
Firebase now also offers Data Connect, which puts a managed Postgres behind a GraphQL-style layer. It narrows the gap for teams committed to Google Cloud, but most Firebase apps and tutorials still use Firestore. Check the current docs for each before you commit.
When is Supabase the right choice?
Supabase is the right choice for B2B SaaS, dashboards, marketplaces and internal tools: products where records relate to each other and you'll want reports across them. You get a real Postgres database on day one, plus auth and storage, without running servers.
Pros
- Relational data, joins and SQL reporting from the start
- Row-level security enforces tenant isolation in the database
- Open source, so you can self-host or move to any Postgres host
- Works well with typed query tools and Next.js server components
Cons
- Row-level security policies need care and testing to get right
- Offline-first mobile sync is less mature than Firebase's
- You still need to design schemas and write migrations
- Heavy reliance on its client SDK from the browser can blur where logic lives
For the full stack around it, see our SaaS MVP tech stack guide. If you're deciding whether to hire for this work or bring in a team, our comparison of in-house teams vs a design-and-dev studio covers the trade-offs.
When is Firebase still the better pick?
Firebase is still the better pick for mobile-first consumer apps, chat and collaboration features, and products that need offline support with automatic sync. Its client SDKs handle reconnects and local caching on iOS, Android and the web, which is genuinely hard to rebuild yourself.
It also suits teams already deep in Google Cloud, and prototypes where speed to a first demo matters more than reporting. The cost shows up later: Firestore rewards data shaped around screens, so cross-cutting questions such as "revenue by plan by month" need duplicated data, exports to a warehouse or a second database. Pricing is based on reads and writes, so model your access patterns against the current pricing page before you scale.
When should you run your own Postgres?
Run your own managed Postgres when you have engineers comfortable with backend work, when compliance or data residency rules narrow your hosting options, or when you want every layer to be swappable. Managed doesn't mean a server in a closet: hosted Postgres services handle backups and upgrades for you.
You'll assemble the rest: an auth provider, file storage, background jobs and real-time if needed. That's more work up front, and you control every piece. Pair it with a typed query builder or ORM, and make sure the whole stack is typed, as we argue in TypeScript for startups. Where tenant checks and data access should live in the app is covered in building a SaaS app with Next.js.
What does it cost to migrate off each one later?
Migrating off Supabase is the cheapest of the managed options, because the data is standard Postgres: you dump and restore it, then replace the auth, storage and real-time pieces you used. Migrating off Firestore is the most expensive, because document data usually has to be redesigned into tables before it moves.
- Supabase out: database dump and restore; export users from auth; move files; rewrite row-level security only if your new setup drops it; replace client SDK calls.
- Firebase out: design a relational schema; write scripts that flatten nested and duplicated documents; migrate users, which can involve password hash compatibility; rewrite every query and real-time listener.
- Custom Postgres out: switch hosts with a dump and restore; your application code barely changes.
Hypothetical example: a SaaS outgrowing Firestore
For example, suppose a team builds a project-tracking MVP on Firestore. Each project document holds its tasks, and each task copies the assignee's name. It's fast to build and the demo works.
A year later, customers ask for workload reports across projects, custom roles per workspace and an audit log. Each needs data that Firestore stores in many places. The team now has to design tables for workspaces, members, projects and tasks, write scripts to reconcile duplicated names, move users, and rewrite every screen's queries. The migration is a project in its own right, which is why the database choice belongs in week one.
Which backend fits your product type?
Match the backend to the shape of your data and your team. Relational, reporting-heavy products belong on Postgres. Real-time, mobile-first products are where Firebase earns its place. Teams with backend skills and strict requirements should own their Postgres.
