Introduction to BaaS

Introduction to BaaS #

What is Backend as a Service #

BaaS provides app (or frontend) developers with an easy way to get backend functionality without having to build a full-blown backend from scratch.

A BaaS consists of a bunch of tightly integrated services that each solve part of what you would need from a backend. These services commonly include:

  • Authentication and authorization
  • Database management
  • Blob storage
  • Notification service
  • Cloud functions

Although there are similarities between services from various BasS providers they are not interoperable. Each provider has their own SDK which gives you access to everything they offer bundled up a single package.

Choosing a provider #

Flutter is backed by Google. They are also behind Firebase. So naturally Firebase and Flutter works very well together. The problem with Firebase is that you need to sign up with a payment card in order to use cloud functions. It is fine if you are building a product, but it might not be something you want to do if you are just making projects to learn.

Firebase is a great BaaS, as long as you don’t mind vendor locking and entering your payment card info. Because that could be a roadblock for some, I’ve considered multiple alternatives. Among those are:

Severpod is not technically a BaaS, but a backend framework for Dart.

What I was looking for is:

  • Mature enough for production use.
  • Cloud hosted (managed)
  • Doesn’t require credit card
  • Can do:
    • Authentication
    • Realtime database
    • Cloud functions

I found Supabase to be the most viable.

You can read how Supabase developers phrase the differences between it and Firebase here.

Supabase #

Supabase is open source and built around PostgreSQL. You can access PostgreSQL directly if you desire. In addition, it provides the following features:

  • Auto-generated API for clients.
  • Realtime changes.
  • Authentication/Authorization with social media login and SSO (single sign-on).
  • Edge functions (aka cloud or serverless functions), which allows you to write server code without writing a full-blown backend or managing servers.
  • Storage for hosting blobs like images, videos etc.

Given that Supabase is built on PostgreSQL, you might be tempted to want to write SQL directly in your Flutter app. Even though it is technically possible to establish a connection directly to PostgreSQL from Flutter, this should be avoided. Your frontend is not supposed to talk directly to the database. Flutter apps should use the auto-generated API.

The auto-generated API simplifies writing queries for the database. And avoids the need to expose the database directly in your app, which would otherwise have some serious security implications.

Consider the schema below:

Supabase countries schema

You can fetch countries with a list of cities just by:

final data = await supabase.from('countries').select('id, name, cities(id, name)');

And you get a result like this:

[
  {
    "id": 1,
    "name": "United Kingdom",
    "cities": [
      { "id": 1, "name": "London" },
      { "id": 2 "name": "Manchester" }
    ]
  },
  {
    "id": 2,
    "name": "United States",
    "cities": [
      { "id": 3, "name": "Los Angeles" },
      { "id": 4 "name": "New York" }
    ]
  }
]
July 17, 2025