Firebase vs Supabase: which one you should actually pick

By Gerald · 29 July 2026

Aerial view of a paved road splitting into two directions through dense green forest

The short answer: pick Firebase if you are building a mobile-first app that needs proven offline sync and you are already deep in Google's ecosystem. Pick Supabase if you want a real Postgres database under your app, predictable relational modeling, and a cleaner path to leaving if you ever need to.

Neither one is the wrong choice. They solve different problems and they fail differently once you scale, which is the part most comparisons skip.

Firebase and Supabase are not really competing on features anymore. They are competing on what it costs you to change your mind later.

The real difference: document store versus Postgres

Firebase's core data product is Firestore, a NoSQL document database. You store JSON-like documents in collections, and you query them with Firebase's own client-side query rules rather than SQL. It is fast to start with and forgiving of a schema that is not fully decided yet.

Supabase's core data product is a real, unmodified PostgreSQL database. Every table is a Postgres table. You can connect any Postgres client, write raw SQL, add extensions, and use joins the way a relational database expects. Supabase adds Auth, Storage, Edge Functions, and a generated API layer around that database, but the database itself is not a proprietary abstraction.

This single decision cascades into everything else. Firestore rewards apps whose data is naturally document-shaped: a user profile, a chat message, a product listing. It gets awkward fast for data that is naturally relational, like orders that reference customers that reference addresses, where you either denormalize aggressively or write more application code to fake a join. Postgres was built for exactly that kind of data, and Supabase inherits that strength directly.

Firebase does offer a newer path for teams who want SQL: Firebase Data Connect, a schema-driven service backed by Cloud SQL for PostgreSQL. As shown on Google's official pricing page in July 2026, Data Connect operations are free up to 250,000 per month, then billed per million after that, on top of the Cloud SQL instance cost, which starts around $9.37 a month after an initial trial period. It closes a real gap for Firestore's query limitations, but you are still paying for a second, separate database service alongside Firestore rather than using one consistent data model.

Auth, storage, and functions compared

Close-up of a data center server cabinet with dense colored cabling running between units — Whichever backend you pick, the exit cost shows up two years later, not on day one.

Both platforms bundle the same four pillars: authentication, a database, file storage, and serverless functions. The implementations diverge in how much you configure versus how much is decided for you.

	Firebase	Supabase
Database	Firestore (NoSQL), or Data Connect (Postgres)	PostgreSQL
Auth	Firebase Authentication, deeply tied to Google identity tooling	Supabase Auth, built on Postgres with row level security
Authorization model	Security rules written in Firebase's own rules language	Row level security policies written in SQL
Storage	Cloud Storage for Firebase	Supabase Storage, backed by S3-compatible storage
Functions	Cloud Functions for Firebase	Edge Functions on Deno
Realtime	Firestore listeners, mature and battle-tested	Realtime via Postgres changes or broadcast

Firebase Authentication is the more mature product by years, with wide platform SDK coverage and deep hooks into other Google services. Supabase Auth is newer but ties directly into Postgres row level security, so a single policy defined once in the database enforces access everywhere, including direct API calls that bypass your application code entirely. That is a real architectural advantage if your authorization logic is more than "logged in or not."

Offline and mobile sync

This is where Firebase still wins outright, and I want to say that plainly rather than hedge it. Firestore's offline persistence has been refined since 2017 and it works reliably across flaky mobile connections, with automatic conflict resolution and a local cache that keeps an app usable with no signal at all. If you are building a mobile app where users genuinely go offline, an airline app, a field service tool, a note app for people underground or in transit, Firestore's offline story is proven at a scale Supabase has not matched.

Supabase does not offer equivalent built-in offline sync as of mid-2026. You can build offline behavior yourself on top of Postgres, using local storage and a sync layer you write, but it is not a feature the platform hands you the way Firestore does. If offline reliability is your primary requirement, this one fact should end the debate before you read the rest of the comparison.

How each pricing model surprises you

Firebase's Spark (free) plan gives you, according to the official pricing page checked in July 2026, 50,000 Firestore reads and 20,000 writes per day, 1 GiB of stored data, and 50,000 monthly active users for Authentication. Past that, the Blaze plan bills per operation: $0.06 per 100,000 reads, $0.18 per 100,000 writes, $0.02 per 100,000 deletes.

The surprise here is operational, not architectural. Firestore bills you for read and write volume, not stored data size. A chatty app with a lot of small reads can rack up cost even with a tiny database, and it is easy to miss until a usage spike shows up on the bill.

Supabase's free tier, per the current pricing page, includes a 500 MB database, 1 GB file storage, 5 GB egress, and 50,000 monthly active users, but free projects pause automatically after seven days with no API activity. A paused project stays intact but takes 20 to 30 seconds to wake on the next request, which is a bad surprise for a side project you check on rarely, or a demo you did not expect anyone to open right before a meeting. The Pro plan is $25 a month, includes 8 GB of database storage before per-GB overage charges, and removes the pause behavior entirely.

The tiebreaker for most small teams is rarely the feature grid. It is whether your traffic shape matches Firestore's per-operation billing or Supabase's storage-and-compute billing, and whether you can tolerate a paused free project waking up slowly at the worst possible moment.

Lock-in and what leaving costs

Leaving Supabase costs you a pg_dump. Your data lives in standard Postgres, so exporting it, self-hosting it, or moving it to any other Postgres provider is a solved, ordinary problem. Supabase itself supports self-hosting via Docker if you decide the managed platform is not worth the price at your scale, and the local development CLI runs the same stack.

Leaving Firebase costs considerably more. Firestore's document model and query language are not portable to another database without meaningful rewrite work. Security rules, written in Firebase's own rules language, do not translate to any other platform.

There is no official self-hosted Firebase, either. Build deeply on Firestore, Cloud Functions, and Firebase Auth, and you are choosing a platform relationship, not just a database. That is a fair tradeoff only if you have made peace with staying.

This is the quiet, structural reason I lean toward recommending people evaluate Supabase first for anything server-heavy: not because Firebase is worse today, but because the door out is a lot narrower.

Who should choose which

Choose Firebase if you are building a mobile app that must work well offline, or if your team is already invested in the Google Cloud ecosystem. It also makes sense if your data is genuinely document-shaped and you do not expect to need complex relational queries.

Choose Supabase if you want a database you can query with standard SQL and connect to standard tools, or if your data model has real relationships between entities. It is also the better pick if you want row-level authorization enforced at the database layer, or if keeping a realistic exit path matters to you as much as today's feature set.

I did not build Flow on either of these. I chose Convex because Flow's notes and tasks need to update live across devices with minimal custom sync code, which is a narrower need than most apps have. If you are picking between Firebase and Supabase specifically, the offline-versus-Postgres tradeoff above is the one that should decide it, not the marketing pages.

Frequently asked questions

Is Supabase a drop-in replacement for Firebase? No. The data models are fundamentally different: Firestore is a NoSQL document store and Supabase runs on relational Postgres. Migrating an existing Firebase app to Supabase means redesigning your schema and queries, not swapping a connection string.

Which is cheaper at small scale, Firebase or Supabase? Both have usable free tiers. Firebase's Spark plan is generous for low read and write volume but bills per operation past that, which can surprise a chatty app. Supabase's free tier is generous on storage and MAU but pauses projects after seven days of inactivity, so an idle side project needs a cold start every time you check on it.

Does Supabase have offline support like Firestore? Not built in. Firestore's offline persistence and automatic sync are a mature, proven feature. Supabase does not ship equivalent offline sync as of mid-2026; you would need to build a local caching and sync layer yourself on top of Postgres.

Can I self-host Supabase but not Firebase? Yes. Supabase supports self-hosting through Docker or its CLI, running the same Postgres-based stack you get from the managed platform. There is no official self-hosted version of Firebase.

Which one is better for a mobile app? If offline reliability is a hard requirement, Firebase's Firestore is the safer choice today. If your mobile app is mostly online with occasional connectivity gaps and you value a relational data model, Supabase is a reasonable choice with more portability.

My verdict

If you are building something mobile-first that has to work with no signal, take Firebase and stop debating it. For nearly everything else, especially anything with relational data or a team that might want to leave one day, I would start with Supabase and only reach for Firebase's document model if your data genuinely does not fit a relational shape.