Supabase or Firebase? A 2025 Comparison Through a Real Project

I’m going to build a project…

Then came the Supabase or Firebase debate.

An idea comes to mind.
“I could build that,” you think.

A mobile app with a web version. Users sign in, create content, leave comments, perhaps like posts and receive notifications…

On day one, you already face the question:

“What should I use for the backend?”

This is where people usually encounter Firebase and Supabase.

I went through the same process.
So I’ll approach this article as if we were building a real project, rather than simply filling out a comparison table.

No marketing.
No brand loyalty.

Just the practical trade-offs.

Let’s Define a Concrete Example Project

Let’s avoid abstractions.
We’ll define a specific project and then consider it with two different backends.

🎯 Example: A Content-Sharing Platform, or Small Social App

Users will be able to:

• Register and sign in

• Create a profile

• Publish posts

• Comment on posts

• Like posts

• Upload profile pictures and post images

• Receive notifications about comments, likes and other activity

Behind the scenes, we need:

• Authentication

• A database

• File storage

• Security and authorisation

• Real-time events

• Long-term scalability

Let’s examine these requirements in the order we would encounter them.

1️⃣ Start with the Data Model — a Critical Decision

A major mistake in a project is thinking:

“I’ll choose the technology first and consider the data later.”

The order should be reversed.

Does this project have relationships between data?
Yes, plenty.

• One user → many posts

• One post → many comments

• One user → likes many posts

• Users → follow other users

Reading that list reveals something important:

“This project is relational.”

That is where one of the biggest differences between Supabase and Firebase begins.

2️⃣ The Firebase Approach: Start Quickly

Firebase’s philosophy is clear:

“Focus on the product rather than building the backend.”

It does this very well.

What Does Firebase Do Well?

• Quick setup

• Ready-to-use authentication

• Real-time capabilities

• Strong mobile support

• Integration with Google’s ecosystem

For example, you want to add a post.

import { getFirestore, collection, addDoc } from "firebase/firestore";

await addDoc(collection(db, "posts"), {
  userId: "uid_123",
  title: "İlk post",
  createdAt: Date.now()
});

Notice what you do not need to define first:

• A table

• A schema

• A migration

Write the data and move on.

What Happens as the Project Grows?

Firebase’s document database is NoSQL.

This means:

• No SQL joins

• No database-enforced relational structure

• Data organisation is up to you

As complexity increases, you may encounter:

• The same data stored in several places

• Risks of inconsistency

• Extra code for complex queries

• Separate reporting systems

Firebase can help you move very quickly at first,
but as a project grows, technical debt can accumulate.

3️⃣ The Supabase Approach: Build a Strong Foundation

Opening Supabase can feel familiar:

“This is the SQL I know.”

Underneath it is PostgreSQL.

A mature database used for years in enterprise environments.

Supabase’s Strengths

• SQL

• Joins

• Foreign keys

• Views, functions and triggers

• Row Level Security

Fetch a post and its comments in one query:

const { data } = await supabase
  .from("posts")
  .select("id, title, comments(id, text, user_id)")
  .eq("id", 1);

At this point, you might think:

“That’s a relief.”

But Supabase requires effort too:

• Plan the data model from the start

• Write RLS policies

• Understand migrations

In this sense, Supabase is:

• More structured

• More focused on explicit engineering decisions

• Comfortable for long-term development

4️⃣ Authentication

Firebase Auth

• Well established

• Strong on mobile

• Ready-made Google, Apple and SMS authentication

Supabase Auth

• Integrated with SQL

• Works alongside the database

Firebase is somewhat more plug-and-play,
Supabase offers somewhat more explicit control.

5️⃣ Security

Firebase Security Rules

Powerful, but potentially complex.

Incorrect rules can leave you with:

• Too much access

• Or a system that does not work

Supabase RLS

One of Supabase’s strongest capabilities.

You answer “Who can see this row?” at the database level.

6️⃣ Real-Time Features and Notifications

Firebase has an advantage in this comparison.

• Chat

• Live data

• Push notifications

These are strong areas for Firebase.

Supabase also offers real-time features, although in this comparison they feel:

• Less integrated than Firebase’s

• More like an additional capability

7️⃣ Pricing and Plans

Now for the part everyone asks about.

Firebase Pricing

Firebase offers two plans.

Spark Plan — Free

Usually sufficient for small projects.

Blaze Plan — Pay as You Go

Firebase costs increase with usage.

Supabase Pricing

Supabase uses a simpler pricing model.

Free Plan

Pro Plan

Team Plan

8️⃣ Building the Same Project with Two Approaches

🔵 With Firebase

Strategy: a quick MVP

• Auth → Firebase Auth

• Database → Firestore

• Storage → Firebase Storage

• Notifications → FCM

Risk:
Complexity and costs may increase as data relationships grow.

🟢 With Supabase

Strategy: a strong data model

• Auth → Supabase Auth

• Database → PostgreSQL

• Security → RLS

• Storage → Supabase Storage

Risk:
More planning is needed at the beginning.

9️⃣ A Practical Decision Guide

Choose Firebase when:

• Real-time interaction is important

• The app includes chat

• You need a quick MVP

• Data relationships are simple

Choose Supabase when:

• There are many related records

• You need SQL

• Reporting matters

• You are planning a long-term product

Conclusion

“Which is better?” is not the most useful question.

A better question is:

What demands will my project place on its backend?

If you find yourself thinking:
“My project’s data relationships will grow” → consider Supabase.

If instead you think:
“I need it working quickly and will refine it later” → consider Firebase.

Remember:

Technology choices shape a project’s future.