TL;DR
Both Firebase Auth and Supabase Auth are secure, production-ready authentication systems. Firebase has more mature mobile SDKs and phone authentication. Supabase Auth integrates seamlessly with PostgreSQL RLS through the auth.uid() function. Both support MFA, social login, and email/password. Choose based on your database preference and SDK needs.
Feature Comparison
| Feature | Firebase Auth | Supabase Auth |
|---|---|---|
| Email/Password | Yes | Yes |
| Social Login (Google, GitHub) | Yes (many providers) | Yes (many providers) |
| Phone/SMS Auth | Yes (mature) | Yes |
| Magic Links | Yes (email link) | Yes |
| Multi-Factor Auth | Yes (SMS, TOTP) | Yes (TOTP) |
| Anonymous Auth | Yes | Yes |
| Custom Claims | Yes | Yes (via user metadata) |
| Token Type | JWT | JWT |
Database Integration
Firebase Auth + Firestore
Firebase Auth integrates with Firestore security rules through the request.auth object:
- Access
request.auth.uidto get the authenticated user's ID - Check
request.auth.tokenfor custom claims - Rules are evaluated on every read/write operation
- Works seamlessly with Firebase's ecosystem
Supabase Auth + PostgreSQL
Supabase Auth integrates with PostgreSQL RLS through SQL functions:
- Use
auth.uid()in RLS policies to get the current user - Access
auth.jwt()for the full JWT payload - Policies are PostgreSQL statements, familiar to SQL developers
- Authentication state is available in all database queries
Key Difference: Supabase Auth is tightly coupled with PostgreSQL. The auth schema stores users directly in your database. Firebase Auth is a separate service that Firestore references via rules.
Password Security
| Security Feature | Firebase Auth | Supabase Auth |
|---|---|---|
| Password Hashing | bcrypt (handled by Google) | bcrypt |
| Password Strength | Configurable requirements | Configurable requirements |
| Breach Detection | Yes (Identity Platform) | No (manual integration) |
| Password Reset | Email with secure link | Email with secure link |
Both platforms use bcrypt for password hashing and support customizable password requirements. Firebase's Identity Platform (paid upgrade) includes password breach detection.
Token Security
Both platforms use JWT tokens with similar security characteristics:
- Short-lived access tokens: Both use tokens that expire (typically 1 hour)
- Refresh tokens: Long-lived tokens for obtaining new access tokens
- Secure storage: SDKs handle secure token storage appropriately per platform
Security Note: Never store tokens in localStorage for sensitive applications. Both platforms' SDKs use more secure storage mechanisms when available.
Multi-Factor Authentication
| MFA Feature | Firebase Auth | Supabase Auth |
|---|---|---|
| SMS OTP | Yes | No (phone auth is separate) |
| TOTP Apps | Yes | Yes |
| Hardware Keys | No | No |
| Enforcement | Per-user or required | Per-user optional |
Firebase has more mature MFA support with SMS as a second factor. Supabase focuses on TOTP (authenticator apps) for MFA.
Admin Capabilities
Firebase Admin SDK
- Create and manage users programmatically
- Set custom claims for role-based access
- Revoke refresh tokens
- Import users from other systems
- Generate sign-in links
Supabase Service Role
- Bypass RLS for admin operations
- Direct access to auth schema
- Manage users via SQL or API
- Set user metadata and app metadata
- Invite users via email
Critical: Neither the Firebase Admin SDK credentials nor the Supabase service role key should ever be exposed to the frontend. Both give unrestricted access to user data.
SDK and Platform Support
| Platform | Firebase Auth | Supabase Auth |
|---|---|---|
| Web (JavaScript) | Excellent | Excellent |
| React Native | Excellent | Good |
| iOS Native | Excellent | Good |
| Android Native | Excellent | Good |
| Flutter | Excellent | Good |
Firebase has been around longer and has more battle-tested mobile SDKs. Supabase's SDKs are newer but rapidly improving.
Which Should You Choose?
Choose Firebase Auth If:
You're building mobile apps and need mature SDKs, want SMS-based MFA, need phone number authentication as a primary method, or are already using Firebase services.
Choose Supabase Auth If:
You want tight PostgreSQL integration with RLS, prefer SQL-based access control, need users stored in your own database, or are building primarily for web with some mobile.
Which is more secure?
Both are equally secure when properly configured. Firebase Auth is backed by Google's security infrastructure. Supabase Auth is open-source and auditable. Security depends more on your implementation than the platform choice.
Can I migrate users between platforms?
Migrating is complex because password hashes aren't directly compatible. You'd need to either: require password resets for all users, or use a gradual migration that re-hashes on next login. Neither platform makes this easy.
Can I use Firebase Auth with Supabase database?
Technically yes, but you lose the auth.uid() integration with RLS. You'd need to verify Firebase tokens in your backend and manually manage user references. It's not recommended unless you have a specific need.
Which has better rate limiting?
Firebase has more aggressive built-in rate limiting and abuse detection. Supabase provides rate limiting but may require additional configuration for high-security scenarios.