title: "🔐 Difference between nextAuth, firebase and supabase" date: "2024-01-10" description: "A deep comparison of the three most popular auth systems used with Next.js."

NextAuth vs Firebase Auth vs Supabase Auth

Choosing the right authentication layer is a strategic decision.
Here’s a practical breakdown based on real-world usage, scalability, dev experience, pricing, and complexity.

1. Core Difference

NextAuth

NextAuth is an authentication framework, not an auth provider.
It manages sessions, tokens, callbacks, and OAuth, but you store your own users.

Firebase Auth

Firebase provides a hosted authentication system.
Google manages user credentials, tokens, security, rate limits, and infrastructure.

Supabase Auth

Supabase Auth is an open-source Firebase alternative, using Postgres as the identity store and GoTrue as the auth server.

2. When to Use What

Use NextAuth if:

• You need custom logic (roles, permissions, metadata).
• You want full control over your DB (MongoDB, Postgres, PlanetScale).
• You want server-side sessions for SSR-heavy apps.
• You require deep integration with your own backend.

Use Firebase if:

• You want zero backend setup.
• You want mobile-first SDKs.
• You don’t care about vendor lock‑in.
• You need built-in MFA, phone auth, social login with zero config.

Use Supabase if:

• You want Firebase features but fully open-source.
• You need Postgres-level relational power.
• You want RLS (Row-Level Security).

3. Code Comparison

NextAuth Example

import NextAuth from "next-auth";
import GitHub from "next-auth/providers/github";

export default NextAuth({
  providers: [GitHub],
  callbacks: {
    async session({ session, token }) {
      session.user.id = token.sub;
      return session;
    },
  },
});

Firebase Example

import { getAuth, signInWithEmailAndPassword } from "firebase/auth";

const auth = getAuth();
await signInWithEmailAndPassword(auth, email, password);

Supabase Example

const { data, error } = await supabase.auth.signInWithPassword({
  email,
  password,
});

4. Pricing & Scalability

Firebase

• Free tier is good.
• But cost spikes with high MAU.
• Vendor lock‑in makes migrating expensive.

Supabase

• Transparent pricing.
• Postgres performance is predictable.

NextAuth

• Your cost = Your database + server usage.
• Scaling depends on your infra.

5. Final Summary Table

| Feature | NextAuth | Firebase | Supabase | | ----------- | ----------- | ----------- | ----------------- | | Control | Full | Low | Medium | | Open-source | Yes | No | Yes | | Cost | DB-based | Consumption | Flat-ish | | Ideal for | Custom apps | Mobile apps | SaaS & dashboards |