TL;DR
Both platforms are secure when configured properly. Supabase uses PostgreSQL with Row Level Security (RLS), giving you SQL-based access control. Firebase uses document-based security rules with its own syntax. The main difference: Supabase's RLS is enforced at the database level, while Firebase rules sit above the database. Choose based on your team's familiarity with SQL versus Firebase's rule language.
Security Model Overview
Supabase and Firebase take fundamentally different approaches to security. Understanding these differences is crucial for making the right choice and avoiding common mistakes.
| Feature | Supabase | Firebase |
|---|---|---|
| Database Type | PostgreSQL (relational) | Firestore (NoSQL document) |
| Security Model | Row Level Security (RLS) | Security Rules |
| Rule Language | SQL policies | Firebase Rules DSL |
| Enforcement Level | Database level | API level |
| Default Security | RLS disabled (open) | Production mode (locked) |
Database Security
Supabase: Row Level Security
Supabase uses PostgreSQL's Row Level Security feature. You write SQL policies that determine who can access which rows. RLS is enforced at the database level, meaning even direct database connections respect your policies.
Warning: RLS is disabled by default in Supabase. You must explicitly enable it on every table that contains sensitive data. This is the most common security mistake in Supabase projects.
Firebase: Security Rules
Firebase uses its own rules language that sits between your app and the database. Rules are evaluated on every read/write operation and can reference authentication state, document data, and incoming writes.
Note: Firebase's test mode allows all reads and writes. Always switch to production rules before launching. Firebase will warn you about insecure rules in the console.
Authentication Security
| Feature | Supabase Auth | Firebase Auth |
|---|---|---|
| Email/Password | Yes | Yes |
| Social Providers | Google, GitHub, Discord, etc. | Google, Facebook, Twitter, etc. |
| Phone Auth | Yes | Yes |
| Magic Links | Yes | Yes (email link) |
| MFA Support | Yes (TOTP) | Yes (SMS, TOTP) |
| Anonymous Auth | Yes | Yes |
| Token Type | JWT | JWT |
Both platforms offer similar authentication features. Firebase has been around longer and has more mature SDKs for mobile platforms. Supabase's auth integrates seamlessly with RLS through the auth.uid() function.
API Key Security
Supabase Keys
- Anon key: Safe for frontend, respects RLS policies
- Service role key: Server-only, bypasses RLS completely
Firebase Keys
- API key: Safe for frontend, used for identification
- Admin SDK credentials: Server-only, bypasses security rules
Critical: Never expose Supabase's service role key or Firebase's Admin SDK credentials in frontend code. Both give unrestricted database access.
Common Security Mistakes
| Mistake | Supabase | Firebase |
|---|---|---|
| Missing access control | Forgetting to enable RLS | Using test mode in production |
| Overly permissive rules | USING (true) policies | allow read, write: if true |
| Key exposure | Service role key in frontend | Admin credentials in frontend |
| Auth bypass | Not checking auth.uid() | Not validating request.auth |
Security Testing
Testing security rules is essential for both platforms:
- Supabase: Test RLS policies using the SQL editor with different roles, or use the Supabase client in your test suite
- Firebase: Use the Rules Playground in the Firebase console, or the Firebase Emulator Suite for local testing
Which Should You Choose?
Choose Supabase If:
You're comfortable with SQL, need relational data, want database-level security enforcement, or prefer open-source solutions. Supabase is great for teams with PostgreSQL experience.
Choose Firebase If:
You're building mobile apps, prefer NoSQL document databases, want the most mature SDK ecosystem, or need real-time sync as a core feature. Firebase's security rules are well-documented and battle-tested.
Security Verdict
Both platforms can be equally secure when properly configured. The biggest risks come from misconfiguration, not the platforms themselves:
- Supabase requires you to remember to enable RLS on every table
- Firebase requires you to switch from test mode before launching
- Both require you to write proper access control rules
- Both have admin credentials that must stay server-side only
Choose based on your data model preferences and team expertise, not security concerns. Either platform will serve you well if you follow security best practices.
Is Supabase more secure than Firebase?
Neither platform is inherently more secure. Supabase enforces security at the database level with RLS, while Firebase enforces it at the API level with security rules. Both approaches are effective when properly implemented. The security depends on how well you configure and maintain your access control policies.
Can I use Firebase security rules with SQL databases?
No. Firebase security rules only work with Firestore and Realtime Database. If you want SQL with similar rule-based security, Supabase's RLS provides equivalent functionality using PostgreSQL policies instead of Firebase's custom rule language.
Which platform has better authentication security?
Both platforms offer industry-standard authentication with similar features: social login, MFA, password hashing, and JWT tokens. Firebase has more mature mobile SDKs due to its longer history. Supabase's auth integrates more seamlessly with PostgreSQL through built-in functions like auth.uid().
What happens if I forget to enable RLS in Supabase?
Without RLS, anyone with your anon key can read and write all data in that table. The anon key is public and can be found in your frontend code. This is why enabling RLS is critical before going to production with any table containing user data.