Supabase or Firebase in 2026: which one to choose for your project?

Short answer: Firebase to prototype fast, especially a mobile app inside the Google ecosystem; Supabase as soon as the data turns relational, when SQL matters or when lock-in worries you. Both are serious products. But they do not rest on the same foundation, and it is that foundation, not the feature list, that should guide your choice.

I have been building on both for years, and my own SaaS runs on Supabase. Here is how I decide, criterion by criterion, without dogma.

In short

• Firebase (Google): a document-oriented NoSQL database (Firestore), free up to 50,000 reads and 20,000 writes per day, then pay-as-you-go per operation, hard to forecast.
• Supabase: managed PostgreSQL, open source, free plan (500 MB database, 50,000 monthly active users), then a Pro plan at $25 per month with 8 GB of database and 100,000 active users included.
• For AI: Supabase integrates pgvector natively (vector search, RAG); Firebase has no native equivalent as mature.
• Exit: a standard PostgreSQL export (pg_dump) with Supabase; with Firebase, a migration measured in days or weeks of work.
• My experience: on 2 out of 3 projects that start on Firestore and grow, data modeling becomes the number one friction point.

The fundamental difference: Google-driven NoSQL vs open PostgreSQL

Everything else flows from there. Firestore, Firebase's database, stores JSON documents in collections. It is very quick to get started with: no schema to define, you push objects and it works. The trade-off comes later: no joins, limited queries (no complex OR, no free aggregations, composite indexes to declare one by one), and modeling through denormalization: you duplicate data so you can read it, and you pay for each duplication in writes and in consistency to maintain yourself.

Supabase puts PostgreSQL at the center: relations, joins, transactions, views, integrity constraints, and the whole ecosystem of extensions, including pgvector for vector search. It is a database with 30 years of maturity, with a language (SQL) that every back-end developer knows.

Second structural difference: Firebase is a proprietary Google product, Supabase is open source and self-hostable. You can run Supabase on your own servers if sovereignty requires it, or simply leave with your PostgreSQL database at any host. With Firebase, your data and your logic live in a format that only Google operates.

Criterion by criterion

• Data model. Nested documents with Firestore: perfect for self-contained objects (profiles, messages), painful as soon as there are relations (customers, orders, invoices). Relational tables with Supabase: a schema to design upfront, but data that is consistent by construction.
• Complex queries. Firestore's acknowledged weak point: no joins, limited aggregations, and some simple questions ("customers who ordered X but not Y") become application-level gymnastics. In SQL, it is one query.
• Authentication. Both are solid and cover the essentials (email, OAuth, magic links). The nuance is in authorization: Firestore security rules are a homegrown language; PostgreSQL RLS policies are written in SQL, apply at the database level itself and enable fine-grained, auditable multi-tenancy.
• Real time. Firebase's historical advantage: Firestore listeners and mobile offline mode remain the most mature on the market. Supabase Realtime (database changes broadcast over WebSocket) covers classic web needs well, but mobile offline is more hand-crafted there.
• File storage. A tie, or nearly: Cloud Storage on the Firebase side, Supabase Storage on the Supabase side, both do the job with built-in access rules.
• AI and vectors. A clear gap in 2026: Supabase offers pgvector natively, so embeddings, semantic search and RAG directly in the database where your business data already lives. On the Firebase side, you have to step outside the platform or assemble separate Google Cloud building blocks: no native equivalent.
• Pricing. Firebase is full pay-as-you-go (Blaze plan): 50,000 Firestore reads and 20,000 writes free per day, then every operation is billed. The trap is not the unit price, which is low, but predictability: one poorly designed screen that re-reads an entire collection, and the bill takes off, with no native cap. Supabase is more readable: free to start, then $25 per month on the Pro plan (8 GB database, 100,000 active users, 250 GB of outbound traffic included), and usage beyond that. Most of the SaaS products I see in production stay between $25 and $75 per month.
• Lock-in. The criterion teams systematically underweight. Leaving Supabase: a pg_dump, and your PostgreSQL database moves elsewhere as is. Leaving Firebase: remodeling denormalized documents into relational, migrating auth, rewriting the security rules. It is doable cleanly, I detailed it in migrating from Firebase to Supabase without breaking everything, but it counts in weeks, not hours.
• Mobile ecosystem. Firebase stays ahead: excellent iOS/Android/Flutter SDKs, native push notifications (FCM), Crashlytics, analytics, all integrated. Supabase has good mobile SDKs, but does not cover that periphery.

The cases where Firebase is still the right choice

Let's be honest, Firebase still wins in several situations:

• A simple mobile app, centered on real-time content without complex relations: chat, activity feed, presence. Firestore's offline mode is unbeatable there.
• Push notifications: FCM is free, reliable and native. With Supabase, you have to plug in a third-party service.
• Prototyping: to validate an idea in a few days without designing a schema, Firestore goes faster over the first mile.
• A team already invested in Google: Google Cloud, Analytics, the existing tooling. Ecosystem consistency has real value.

And if your need is neither one nor the other, a small SQL database on the edge for a site or a lightweight API, the question takes a different shape: I compared Supabase and Cloudflare D1 for that specific case.

My production feedback

BeForBuild.com, my B2B SaaS, runs on Supabase in production: PostgreSQL for business data, Supabase Auth for accounts, RLS for multi-tenant isolation (each customer sees only their data, guaranteed at the database level, not just in application code) and pgvector for the RAG of the document assistant. Designed and shipped solo, with no infra team.

Why this choice for a B2B SaaS? Three reasons. First, the data of a B2B product is relational by nature: organizations, users, documents, permissions, subscriptions. Modeling that as denormalized documents means inflicting on yourself in application code what PostgreSQL does for free in constraints and joins. Next, RLS: in B2B, a data leak between two customers is a disqualifying fault; I prefer isolation to be a verifiable SQL policy rather than a code discipline. Finally, AI: the RAG relies on pgvector in the same database as the data it queries, which simplifies the architecture and the access permissions. The details of this stack are on my freelance Supabase developer page.

What it costs to choose well (or to migrate)

The real cost is not the subscription, it is the late migration. Choosing Firestore for a product that will become relational means deferring a debt: by the time the queries get stuck and the bill becomes unreadable, the migration to PostgreSQL (data remodeling, auth, dual-writing to avoid cutting service) represents several weeks of skilled work, often more than what the initial choice would have cost in thought.

On the Buildoto side, two fixed-price offers, price signed before starting: a complete SaaS MVP (PostgreSQL database, auth, multi-tenant, one business feature, deployed to production) from $7,450 excl. tax, in 4 to 6 weeks; and the Firebase to Supabase migration, priced at a fixed rate after an audit of your Firestore model, carried out in stages with dual-writing, with no service interruption.

Where to start

• 1. Put your data model on paper. If you naturally draw arrows between entities (customers, orders, permissions), you are relational: Supabase. If they are self-contained, real-time objects, Firebase holds up.
• 2. Project the bill at 12 months. Estimate Firestore reads/writes on your real usage vs a Supabase Pro plan at $25 per month: the predictability gap is obvious.
• 3. Let's talk about it. I offer a free 30-minute audit: we look at your project (or your existing Firestore), and I tell you honestly whether Supabase is justified, or whether Firebase is enough for your case.

Sources

• Supabase, official pricing grid (Free and Pro plans)
• Firebase, official pricing grid (Spark and Blaze plans)
• Supabase, official guide to migrating Firestore data