Firebase vs Supabase vs Custom Backend:  Which Backend Should You Choose?

When building a mobile app or a web platform, you face a big decision for the backend – the “brain” that handles data, server-side logic, and storage. Here you can choose between a ready-made service like Backend-as-a-Service (BaaS), or build your own custom backend. It is essentially a dilemma between cost vs freedom. Let’s compare two of the most popular BaaS solutions (Firebase vs Supabase) and explore when a custom backend might be the smarter choice.

Custom Backend

A custom backend is the traditional approach: you build and maintain your own server logic, APIs, and database. What does that mean exactly?

Server Logic:
This is the code that runs on your server to handle requests, process data, and perform actions behind the scenes. For example, when a user submits a form, the server decides how to save that data or trigger certain actions.

APIs (Application Programming Interfaces):
APIs are the bridges between your frontend (what users see) and backend (where the data lives). Maintaining APIs means designing, updating, and fixing these bridges whenever your app evolves. APIs can change because you add new features, improve performance, fix bugs, restructure data, or update security. Keeping APIs working correctly ensures your app continues to communicate properly with the backend.

Database:
This is where all your app’s data is stored. With a custom backend, you control the database structure, how data is saved, and its security.

Backend technologies

Popular technology stacks include:

• .NET (C#) – A super-fast, versatile and powerful framework, widely used for all kinds of projects from startups to enterprise-grade applications, APIs, and scalable web services.

• Node.js / Express.js – JavaScript-based, great for real-time applications (chat apps, collaborative tools) and rapid development.

• Spring Boot (Java) – Robust framework ideal for large-scale and enterprise applications.

Custom Backend: Pros and Cons

Disadvantages:

• Slower development and testing compared to BaaS.
• Higher upfront cost because your team builds everything from scratch.
• You are responsible for server maintenance, scaling, and security.

Advantages:

• Full control over architecture, performance, and security; 
• No limitations from third-party platforms—meaning you can implement any feature exactly the way you want. For example, you can create complex database queries or custom workflows that Firebase or Supabase might restrict.
• Easier to handle complex workflows and integrations.

Ideal Use Cases:

• Apps with highly specific or complex requirements, such as fintech or healthcare systems.
• Projects needing full control over data, security, and performance.
• Teams planning long-term growth and avoiding vendor lock-in.

What is BaaS?

Backend-as-a-Service (BaaS) is a cloud-based solution providing ready-made backend functionality. Instead of building your backend from scratch, BaaS providers offer pre-configured features like:

• Databases (SQL or NoSQL) – more on this later in the article
  
• User authentication and authorization – ready mechanisms that “recognise” the user and “let them enter” the app
  
• File storage
  
• Serverless functions, which are small pieces of backend code that run on-demand in the cloud, without you needing to manage a server, e.g. When a user uploads a photo, a serverless function automatically resizes it and stores it in the cloud.
  
• Push notifications
  

Advantages of BaaS:

• Speed: Launch your app quickly.
  
• Reduced Development Work: Many backend tasks are pre-built.
  
• Integrations: Built-in support for analytics, authentication, and storage.
  

Limitations:

• Less control over architecture (how different parts of the system are organized and interact with each other).
  
• Vendor lock-in can complicate future migrations. This means your app becomes tied to a specific service (like Firebase or Supabase). If you later want to switch to another service or run your backend yourself, it can be difficult, time-consuming, and expensive.
  
• Customizing business logic beyond the platform’s features can be challenging.
  

BaaS can be especially useful for MVPs, prototypes, or small teams with limited backend expertise.

Popular BaaS Solutions: Firebase vs Supabase

Firebase

Firebase, now owned and developed by Google, is one of the most popular Backend-as-a-Service platforms. It started in 2011 as a simple tool to help developers build real-time apps—its first product was a database that made chat apps and collaborative tools much easier to create. Over time, Firebase expanded into a full backend ecosystem, including authentication, cloud functions, storage, and analytics, all designed to help developers launch apps faster without managing servers.

Key Features:

• Realtime Database & Firestore: These are databases that update immediately across all devices. For example, in a chat app, when one user sends a message, it instantly appears for everyone else.
  
• Authentication: Handles user login and security. Supports email/password login, Google or Facebook login, and even anonymous accounts for first-time users.
  
• Cloud Functions: Lets you run small pieces of backend code automatically in response to events (e.g. resize a photo when a user uploads it, send a welcome email when a user signs up, update a database record when data changes, etc.)
  
• Analytics & Crash Reporting: Provides tools to track how users use your app and detect errors. For instance, you can see which feature users interact with most or quickly identify why the app crashes for some users.
  

Additional Firebase Tools

Firebase isn’t just a pure backend – it also offers a variety of tools that make development faster and easier.

• FireCMS, for example, is a ready-made admin panel that lets you manage your Firestore data without building a custom dashboard. 
• Firebase Extensions are pre-built solutions for common tasks, such as resizing images, sending emails, translating text, or integrating with Stripe. 
• Other tools like Crashlytics and Performance Monitoring help you track app stability and performance in real time, so you can quickly detect and fix issues.
  

Together, these tools make it easier for developers to build, manage, and optimize their apps.

Firebase Pros & Cons

Pros:

• Well-established and reliable, used by many large apps.
• Excellent documentation and community support, meaning developers can find solutions quickly.
• Real-time updates work very well, making apps feel responsive and live.
• Firebase offers a set of additional developer tools that are tightly integrated with its ecosystem (e.g. FireCMS).

Cons:

• No in-built SQL support (Firestore is NoSQL) so complex relational queries are harder* (more on this topic below)
• Costs can grow quickly as your app scales and user activity increases.
  

SQL and NoSQL database? What is it and why should you care?

SQL is a language used to ask questions and get data from traditional databases, like “give me all users who bought both Product A and Product B.” These kinds of complex questions are easy in SQL.

Firestore, on the other hand, is a NoSQL database, which stores data differently (in “collections” and “documents”). It’s great for simple, fast access to data (like messages in a chat app), but asking complex questions that involve connecting multiple types of data is harder (not impossible) and sometimes requires extra work.

Is a noSQL database a bad thing?

Not at all! NoSQL databases are not inherently bad, they just have different strengths and trade-offs compared to SQL databases. It depends on your app’s needs. Some of a NoSQL database strengths are: its flexibility (it’s easy to store different types of data), scalability (handles large amounts of data and high traffic efficiently), and speed.

Supabase

Supabase is an open-source Backend-as-a-Service platform built on PostgreSQL, a powerful relational database. It was founded in 2020 with the goal of giving developers a BaaS experience similar to Firebase, but with full SQL support and open-source flexibility. Unlike Firebase, which is proprietary, Supabase lets you see and modify the underlying code, and even self-host it if needed.

Its core features include:

• Database: PostgreSQL with real-time capabilities.
  
• Authentication: Secure and flexible login options for users.
  
• Storage: File hosting and management for images, documents, and other assets.
  
• Edge Functions: Serverless functions to run custom backend logic.j.
  

Supabase is especially popular among developers who want the speed and simplicity of a BaaS without giving up the control and flexibility that SQL and open-source software provide.

Supabase Pros and Cons

Pros:

• Open-source and transparent.
  
• Full SQL capabilities for complex queries. This is useful for reporting, analytics, and business logic that would be more time-consuming in NoSQL systems.
  
• Self-hosting option reduces vendor lock-in risk. You’re not fully tied to Supabase’s cloud. If pricing, policies, or requirements change, you can run Supabase on your own servers and keep your app working with minimal changes.
  

Cons:

• Smaller ecosystem compared to Firebase. There are fewer tutorials, plugins, and third-party tools available, so developers may need to build more things themselves (more time-consuming = costly to build certain functions).
  
• Real-time features are still evolving.
  
• Fewer ready-made integrations. Unlike Firebase, Supabase doesn’t include built-in analytics or AI tools, so you’ll often need external services (like Google Analytics or third-party AI APIs)

General Side-by-side Comparison

Function	Firebase	Supabase
Database Type	NoSQL (Firestore)	SQL (PostgreSQL)
Real-time	Excellent	Good
Serverless Functions	Cloud Functions	Edge Functions
Open Source	No	Yes
Pricing	Usage-based, can scale	Usage-based, generally lower
Vendor lock-in	High	Lower (can self-host)

Firebase vs Supabase vs Custom Backend: Cost Comparison

When comparing BaaS solutions and a custom backend, it’s important to separate service pricing from the overall cost of building and maintaining a backend. 

Firebase and Supabase make it easy to get started with low or no upfront costs, which is especially valuable for MVPs and small teams. Firebase uses a usage-based pricing model that scales naturally with your app’s activity (which from the business perspective should mean you have more paying users any way), while Supabase offers more predictable, plan-based pricing. 

A custom backend can become more cost-efficient at large scale, but it also requires more development time, infrastructure setup, and ongoing maintenance. In many real-world scenarios, using a BaaS is still the most cost-effective choice once development speed and operational effort are taken into account.

Cost comparison by project stage

Stage / Solution	Firebase	Supabase	Custom Backend
Small app / MVP (~1,000 users)	$0–$10 / month Free tier usually enough	$0 / month Free tier	$10–$30 / month Basic server
Growing app (10k–50k users)	$50–$300 / month Costs rise with reads, writes, and real-time usage	$25–$50 / month Fixed plan	$40–$100 / month Larger serve
Large app (100k+ users)	$500–$2,000+ / month Costs can rise considerably when your app is really large	$100–$300 / month More predictable	$200–$600 / month Infrastructure-based
Pricing model	Pay per usage (reads, writes, functions)	Monthly plans + resources	Pay for servers & infrastructure
Best for	MVPs, prototypes, fast launches	Startups that want SQL & control	Long-term, complex systems

Planning for “Unicorn” Growth

It’s natural to imagine your app becoming the next big thing — a “unicorn” — and to want a backend that can handle massive growth from day one. However, even wildly successful apps often start with simpler solutions like BaaS. Using Firebase or Supabase allows you to launch quickly, validate your ideas, and serve early users without investing months or years in building a custom backend upfront.

Rewriting your backend later, or even migrating to a fully custom solution, is not a sign of failure. In fact, most mature systems undergo periodic rewrites every few years to take advantage of new technologies, improve performance, and adapt to changing requirements. 

Starting with a BaaS doesn’t waste effort — it’s a strategic way to launch your app fast, attract users quickly, and scale intelligently.

Cost vs Freedom

The trade-off between backend choices is simple:

• Custom Backend: Higher initial cost, slower launch, but complete control.
  
• BaaS: Fast launch, lower upfront cost, but constrained by platform limits.
  

Example:

• A chat app with standard features can run efficiently on Firebase.
  
• A fintech platform with complex transactions and strict compliance rules is better suited for a custom backend.

Factors to Consider When Choosing a Backend

1. Scalability Needs: Consider how many users your app will have in one 1 year, 2 years, 3 years, and how usage might change. Some apps have steady traffic, while others may suddenly get a large number of users. You need a backend that can handle your expected load.
   
2. Business Logic Complexity: Think about how your app works behind the scenes. Some apps are simple (a note-taking app where users create, read, update, or delete notes), while others have advanced workflows, such as processing payments, managing inventory, or sending notifications automatically. The more complex and non-standard your app, the more control you might need over the backend.
   
3. Budget & Timeline: How quickly do you want to launch, and how much can you spend? Using a BaaS like Firebase or Supabase can get an app running fast, which is ideal for testing ideas or launching an MVP (minimum viable product). Building a custom backend takes more time and resources but may be better for long-term growth.

Practical Guidelines (when choosing between Firebase vs Supabase vs Custom Backend)

• Custom Backend: Best if your app has complex requirements, needs full control, or must comply with strict regulations.
  
• BaaS (Firebase): Ideal for apps that need to launch quickly, support real-time updates, and have small to medium-scale user bases.
  
• BaaS (Supabase): Good choice if you want SQL flexibility, open-source tools, and the ability to migrate or self-host later.
  

Conclusion

There’s no universal solution for a backend and each approach has trade-offs. Custom backends provide maximum freedom and control, while BaaS platforms like Firebase and Supabase allow for rapid development and lower maintenance overhead. By understanding your project’s goals, complexity, and team capabilities, we help you choose the backend that ensures both short-term efficiency and long-term scalability.