Supabase Versus Firebase: Which to Choose for an MVP

Both solve the same problem: a backend for an MVP without writing one. They differ in their foundation, and that difference drives everything else.

The data model

Supabase is a relational database. Tables, relations, foreign keys, SQL. A query with joins is written once and executed in a single round trip.

Firebase is a document store. Data lives as documents with no relations in the usual sense. Queries are simpler, but joining data falls to the application: what SQL does in one query becomes several round trips and assembly on the client.

The practical consequence: the choice follows how interrelated your data is.

Strongly related (orders, line items, customers, statuses) - a relational model is simpler and more predictable.
Loosely related (independent records, feeds, documents) - a document model is more convenient.

A second consequence concerns change: altering data structure is more expensive in a document store. There is no schema, old documents keep their old shape, and the application has to read both.

Cost as you grow

Model it against your own load profile rather than comparing pricing pages: they bill different things.

A document store typically charges for read and write operations. An application that frequently reads small documents accumulates them fast. The classic surprise is a feed refreshing for every user.

A relational database typically charges for resources, storage and traffic. Many small queries are cheap, but one badly written heavy query is felt.

Assess it by asking: which will grow faster, your operation count or your data volume? The answer usually determines which comes out more expensive.

Vendor lock-in

Here the difference is substantial.

Supabase. Ordinary PostgreSQL underneath. The database moves with its schema to any host or to your own server. What has to be rewritten is the surrounding code: authentication, data access, functions. The data itself is yours and in a standard format.

Firebase. Data can be exported, but the model, queries and access rules are tied to the service. Moving means rebuilding the data model, not just changing storage.

A practical rule: the less unique your backend, the less vendor lock matters. For a prototype it is not an argument at all; for a product intended to last years it is.

How to choose

Five questions that settle it:

Is the data interrelated? Yes - relational.
Are you comfortable with SQL? Yes - relational. No - document is simpler at the start.
Is a mobile app with offline support the priority? Offline synchronisation is more developed on the document side.
Are there data residency requirements? Then you need self-hosting, which settles it.
What grows faster, operations or volume? That determines the bill.

And a general note: at prototype scale the difference is small. Both give a working backend in days. The differences appear as you grow, so choose for where you plan to go rather than for the convenience of week one.

What Supabase actually gives you: the guide. Where projects on it break: authentication and RLS.

FAQ

Which should an MVP use, Supabase or Firebase?

If your data is interrelated and you are comfortable with SQL, Supabase is easier: a relational model with joins. If the data is loosely related and the priority is a mobile app with offline support, Firebase covers that better. The data model decides, not the feature list.

Which is cheaper as you grow?

There is no universal answer, because they bill different things: one weights read and write operations more heavily, the other storage and traffic. Model it against your own load profile rather than comparing pricing pages.

Where is vendor lock-in stronger?

In the document store: moving data along with its model to another service is hard. Supabase sits on ordinary PostgreSQL, so the database travels with its schema almost anywhere and only the surrounding code is rewritten.