Supabase vs Firebase: which one to choose

The main difference between Supabase and Firebase is the data model: Supabase is a Postgres database with SQL, relations and row-level access policies; Firebase revolves around Firestore, a NoSQL document database with real-time sync and offline support. Nearly everything else — authentication, storage, functions — both of them have. So the useful question isn’t which is better, but what shape your data has and what leaving will cost you the day you want to.

Both are a backend as a service with a free plan, and both have limits worth reading before you start. The exact numbers change often; here we explain what to look at and link to the source each time.

Supabase vs Firebase in one table

	Supabase	Firebase
Database	Postgres (SQL, relational)	Firestore (NoSQL, documents); also Realtime Database and a PostgreSQL option on Cloud SQL
API	REST and GraphQL generated from your tables	Client SDK for each platform
Access rules	Row-level security (RLS) policies in SQL	Firebase’s own Security Rules
Real time	Yes, on database changes	Yes, with Firestore listeners
Offline	Up to you, in the client	Offline support on mobile and web
Functions	Edge Functions	Cloud Functions, Blaze plan only
File storage	Included in the free plan	Cloud Storage requires the Blaze plan
Free plan	Free, with projects that pause when inactive	Spark, no payment method needed
Open source	Yes (Apache 2.0), self-hostable	No

The data model decides almost everything

If your data is relational — users who have orders, orders that have line items, products that belong to categories — Postgres lets you express it as it is, with foreign keys, joins and transactions. In Supabase you query what you need in one request, and the database guarantees the data stays consistent.

Firestore organises data as documents inside collections. For hierarchical data, or data that’s always read together, it’s very comfortable, and its real strength is on the client: real-time listeners and offline support on mobile and web, which lets the app read and write without a connection and sync when it comes back. If your app is mobile and has to work on the underground, that counts for a lot.

The cost of documents shows up as queries grow: what SQL does with a join usually ends up, in Firestore, as duplicated data or several reads. Google now offers a relational option inside Firebase — a managed PostgreSQL database on Cloud SQL — but it’s a separate product from Firestore, not the way most Firebase apps are built.

What each free plan includes

Supabase Free includes the database, authentication, file storage, real time and Edge Functions. What to watch, per its pricing page: a limited number of active projects, and free projects are paused after a period of inactivity. For a project in development that doesn’t matter; for a demo someone opens once a month, it does. The Supabase directory page has the current limits.

Firebase Spark needs no payment method and includes Firestore, Realtime Database (one per project), authentication and Hosting. What it doesn’t include is what people most often miss:

• Cloud Functions only exists on the pay-as-you-go Blaze plan.
• Cloud Storage also requires Blaze. Firebase announced it in September 2024 and it took effect on 3 February 2026: projects on Spark lose access to their buckets. Blaze still includes no-cost usage, but you have to add a card.

In practice, as soon as a Firebase app needs server-side logic or to upload a photo, it needs a card on file. With Supabase, that point comes later. Free plans change several times a year, so each provider’s official pricing page is the one that counts. Why these differences matter more than gigabytes is covered in the free-plan limits nobody reads.

What leaving costs

It’s the criterion nobody looks at when starting, and the one that weighs most two years in.

Supabase is open source under the Apache 2.0 licence and can be self-hosted with Docker or its CLI. But the important part is something else: underneath is plain Postgres. If you leave, you take a dump and load it into any other managed Postgres; your queries and schema still work. What you’d have to replace is the authentication and the generated API.

Firebase is a Google service with no self-hosted version. Exporting the data is possible, but Firestore’s document shape and its Security Rules have no direct equivalent elsewhere, so leaving means rewriting the app’s data layer.

That’s no reason to rule Firebase out. It’s a cost worth knowing before you choose, as with any piece of a free stack to launch a project.

Supabase or Firebase: when to pick each

Pick Supabase if your data has relations, you know SQL or want to learn it, you care about being able to take the database to another provider, or you need storage and functions without adding a card on day one.

Pick Firebase if it’s a mobile app that must work offline, client-side real time is the heart of the product, you already work inside Google Cloud, or your data is documents that are read and written whole.

If you’re unsure, the rule from free-tier databases still holds: for most projects, Postgres is the most portable choice. And if the backend is going to be your own code rather than a service, see free backend hosting. More services of this kind in data and backend.

Frequently asked questions

What is the main difference between Supabase and Firebase? The data model. Supabase is Postgres, a relational database with SQL. Firebase revolves around Firestore, a NoSQL document database with real time and offline support on the client.

Is Supabase free? It has a Free plan with database, authentication, storage and functions. It caps the number of active projects and pauses projects that have been inactive for a while, so it won’t keep something permanently available without paying.

Does Firebase need a credit card? The Spark plan needs no payment method. But Cloud Functions and Cloud Storage require the pay-as-you-go Blaze plan, so as soon as you need either one you have to register a card, even if your usage stays within the no-cost portion.

Can I migrate from Firebase to Supabase? Yes, and Supabase publishes guides for migrating authentication, storage and Firestore data. The laborious part isn’t moving the data but redesigning it from documents into tables and rewriting the access rules.

Which free backend as a service suits an MVP? For a web app with relational data, Supabase usually goes further without paying. For a mobile app used offline, Firebase. Either way, check the official pricing page before starting, because free plans change.