Supabase vs Firebase (2026): Which Backend Should You Choose?

If you're starting a web or mobile app in 2026 and don't want to build a backend from scratch, you'll almost certainly end up comparing Supabase and Firebase. Both give you a database, authentication, file storage, and serverless functions, with generous free tiers and SDKs that get you from zero to a working app in an afternoon.

They're often described as direct competitors, and in a sense they are. But they're built on very different foundations, and that difference decides which one fits your project far more than any feature checklist does.

Full disclosure before we start: at MyKavo we use Supabase for our own product. I'll explain why, but I'll also be clear about the situations where Firebase is the better choice, because there are real ones.

The one-sentence difference#

Firebase is a Google-built platform centered on a NoSQL document database, designed first for mobile and realtime apps. Supabase is an open-source platform built on top of standard Postgres, a relational SQL database, with auth, storage, and APIs added around it.

Almost every other difference flows from that: how you model data, how you query it, how pricing grows, and how hard it is to leave.

Database: SQL vs documents#

This is the biggest decision, so it's worth slowing down on.

Firebase (Cloud Firestore) stores data as documents inside collections, similar to JSON objects. It's flexible and fast to start with: you can write data without designing a schema first, and reading a single document or a simple list is quick and easy. Realtime updates and offline support are excellent, especially on mobile.

The trade-off shows up as your app grows. Firestore's querying is deliberately limited. The default Standard edition has no joins (the newer Enterprise edition adds join-style queries), so related data is usually duplicated across documents, and keeping those copies in sync becomes your job. On the default Standard edition, reporting questions like "total revenue by country for customers who signed up last quarter" range from awkward to impossible without exporting data elsewhere.

Supabase gives you a full Postgres database. You design tables and relationships up front, and in exchange you get the full power of SQL: joins, aggregations, transactions, constraints that keep your data consistent, views, full-text search, and a huge ecosystem of extensions, including vector search for AI features. Supabase also generates a REST and GraphQL API from your tables automatically, so you don't have to write basic CRUD endpoints.

The trade-off: you need to think about your schema, and relational modeling has a steeper learning curve than dropping JSON into a collection.

Rule of thumb: if your data has lots of relationships, users, teams, orders, invoices, products, permissions, Postgres will save you pain later. If your data is naturally a set of independent documents that sync to devices in realtime, Firestore shines.

Authentication#

Both are strong here.

Firebase Authentication is mature and battle-tested, with email and password, phone, anonymous sign-in, and a wide range of social providers. The free Spark plan includes 50,000 monthly active users.

Supabase Auth also covers email and password, magic links, phone, and many social providers, and it includes 50,000 monthly active users on the free plan (100,000 on Pro). Its standout feature is how it connects to the database: user identity flows straight into Postgres Row Level Security, so you can write rules like "users can only read rows where user_id matches their own ID" once, in the database, and every API request respects them.

One practical note for Supabase: its built-in email service is only meant for testing. It sends a small number of emails per hour and only to your own team's addresses, so for real users you'll need to connect your own email provider through SMTP. Supabase's guide to sending emails with custom SMTP covers the setup.

Security model#

Firebase uses Security Rules, a custom rules language that controls who can read and write which documents. They're powerful but a separate thing to learn, and misconfigured rules are a common cause of exposed data.

Supabase uses Postgres Row Level Security policies, written in SQL. If you know SQL, they're natural to write and test. The key thing to understand is that Supabase's publishable key (and the older anon key) is safe to use in the browser only because RLS protects your tables. A table without RLS enabled, or a secret key leaked into frontend code, exposes your data. Supabase's own production checklist walks through the settings to check before launch, starting with RLS.

Neither is "more secure" by default. Both are secure when configured properly and dangerous when not.

Realtime and offline#

Firebase has the edge for offline-first mobile apps. Firestore's SDKs cache data on the device, let users keep working offline, and sync changes when connectivity returns, with very little code.

Supabase offers Realtime, which lets clients subscribe to database changes, broadcast messages, and track presence, and it works well for live dashboards, chat, and collaborative features. It doesn't offer the same built-in offline-sync experience as Firestore.

Functions and storage#

Both offer serverless functions and file storage, with an important difference on the free tier.

Firebase: Cloud Functions and Cloud Storage are not available on the free Spark plan at all. You need the pay-as-you-go Blaze plan to use them, which requires a billing account.

Supabase: the free plan includes Edge Functions (500,000 invocations a month) and 1 GB of file storage.

If you want to build a complete app with server logic and file uploads without adding a card, Supabase's free tier goes further.

Pricing and free tiers#

Here's what each free tier includes, from their pricing pages this month:

How pricing grows is where they differ most.

Supabase's paid plan starts at $25 a month and is largely predictable: you pay for the plan and your compute size, with usage-based charges above included amounts for things like extra monthly active users, storage, and egress.

Firebase's Blaze plan is pay-as-you-go, charged per document read, write, and delete, plus storage and bandwidth. That's very cheap for small apps. But because you pay per operation, an inefficient query, a page that loads hundreds of documents, or a bug that loops reads can produce a surprising bill. Firebase even publishes its own guide to avoiding surprise bills.

Neither model is wrong. Pay-per-operation is great when usage is small and well-understood. A fixed plan is easier to budget as you grow.

Lock-in and open source#

This is a real difference.

Supabase is open source, and your data lives in standard Postgres. You can export it with standard Postgres tools, self-host Supabase on your own infrastructure, or move to any other Postgres host. Leaving is work, but it's well-trodden work.

Firebase is proprietary. Firestore's data model and Security Rules exist only on Google's platform. Migrating away means reshaping your data and rewriting access rules, which is a much bigger project.

If avoiding lock-in matters to you, this alone may decide it.

Developer experience#

Both have good docs, dashboards, and SDKs.

Firebase has a longer history, a huge community, and deep integration with other Google services: Analytics, Crashlytics, Cloud Messaging for push notifications, Remote Config, and App Check. For mobile apps, that ecosystem is a major advantage.

Supabase feels natural if you know SQL. The dashboard includes a table editor, SQL editor, and security advisors that flag common mistakes, and its local development tooling lets you run the whole stack on your machine. Its TypeScript types, generated from your schema, make frontend work pleasant.

Performance and scaling#

Both platforms scale well past what most apps will ever need, but they scale differently.

Firestore scales automatically. You don't choose server sizes or think about connections, and reads of individual documents stay fast no matter how large the database grows. The limits you feel are in query design: on the default Standard edition, every query needs a supporting index, and some query shapes simply aren't allowed. Scaling Firestore well is mostly about modeling data so the queries you need are cheap.

Supabase runs a dedicated Postgres instance per project, and on paid plans you choose the compute size and move up as you grow. Postgres handles a very large amount of traffic on a single well-sized instance, and Supabase adds connection pooling, read replicas, and query performance tools. Scaling Supabase well is mostly about indexes, efficient queries, and picking the right compute size, the same skills as scaling any Postgres database.

In practice, performance problems on either platform usually come from the app's queries rather than the platform itself.

Can you use both?#

Yes, and some teams do. A common pattern is Supabase for the main relational data and business logic, and Firebase for specific mobile features like push notifications through Firebase Cloud Messaging or crash reporting through Crashlytics. These Firebase services don't depend on Firestore, so you can use them alongside a Supabase backend.

The cost is two platforms to learn, secure, and pay for. For most small teams, picking one as the core and adding the other only for a specific, clear need keeps things simpler.

A quick decision test#

Answer these three questions:

1. Will you need to answer questions that join data together? Revenue by plan, orders by customer, tasks by team member. If yes, lean Supabase.
2. Must the app work well offline on phones? If yes, lean Firebase.
3. Would a surprise bill or being locked in hurt your business? If yes, lean Supabase.

If your answers point in different directions, the first question usually matters most, because your data model is the hardest thing to change later.

When to choose Firebase#

• You're building a mobile-first app that needs offline support and realtime sync.
• You want push notifications, crash reporting, and analytics from one platform.
• Your data is simple and document-shaped, without many relationships.
• Your team already knows Firestore and Google Cloud.

When to choose Supabase#

• Your data is relational: users, teams, orders, subscriptions, permissions.
• You want SQL for querying, reporting, and data integrity.
• You want predictable pricing as you grow.
• You care about open source and being able to move your data.
• You want functions and file storage on the free tier without adding a card.
• You're building AI features and want vector search in the same database as your app data.

What happens after you choose#

Whichever you pick, the backend decision is where the easy part ends. Once your app is live, the problems that actually hurt tend to be operational rather than architectural:

• On Supabase's free tier, a project paused for inactivity takes your app down until someone resumes it.
• On Firebase's free tier, hitting the daily read limit in the evening means errors until the next day.
• A bad data update or an admin edit can change what your live pages show, with no code review involved.
• A security rule or RLS policy change can quietly break sign-up or login for real users.

Your backend's dashboard will tell you about the backend. It won't tell you that your pricing page is now blank because a query returns nothing, or that your sign-up form stopped rendering after a data change.

Where MyKavo fits in#

MyKavo is our product, so to be clear about what it does: MyKavo watches the public pages of your live app, like the homepage, pricing, sign-up, login, and key content pages, and alerts you when something important changes or breaks, such as an error status, missing content, a changed title or meta tag, a removed script, or a missing form or button. Each alert shows the before and after, ranked by severity, sent to email, Slack, Discord, or a webhook.

It works with either backend, because it only looks at what your pages show visitors. If you choose Supabase, there's also an integration: a Supabase Database Webhook or pg_net trigger can start a MyKavo check whenever your data changes, for example when content is published, so you see the effect on your live pages within minutes. MyKavo never connects to your database. (Triggered checks are on the Pro and Agency plans. The free plan monitors one site and five pages weekly.)

It doesn't replace your backend's own monitoring: it won't show query performance, read counts, or database health.

The bottom line#

Choose Firebase if you're building a mobile-first, realtime, offline-friendly app and want Google's ecosystem around it. Choose Supabase if your data is relational, you want SQL and predictable pricing, and you'd like the freedom to move your data later. Both are excellent, and both will get your app live quickly.

Then make sure you know when the live app breaks, before your users tell you. MyKavo watches your app's key pages and alerts you with evidence when something changes or breaks, and works with Supabase so a data change can trigger a check. Start free.