TL;DR
Supabase (PostgreSQL) offers database-level security through Row Level Security policies. MongoDB Atlas provides field-level encryption and role-based access control. Supabase is better for apps needing fine-grained row access control. MongoDB shines when you need flexible schemas with field-level encryption. Both require proper configuration to be secure.
Architecture Differences
Supabase and MongoDB have fundamentally different architectures that affect how you implement security:
| Feature | Supabase | MongoDB Atlas |
|---|---|---|
| Database Type | PostgreSQL (relational) | Document-based (NoSQL) |
| Data Model | Tables with rows and columns | Collections with documents |
| Query Language | SQL | MongoDB Query Language |
| Schema | Strict schema enforcement | Flexible, schema-optional |
| Client Access | Direct with RLS | Typically through API layer |
Security Model Comparison
Supabase: Row Level Security
Supabase exposes your PostgreSQL database directly to the frontend. Security is enforced through RLS policies that filter data at the database level:
- Policies are SQL-based and execute on every query
- Access control is based on user identity from JWT tokens
- RLS must be explicitly enabled on each table
- Policies can reference other tables for complex authorization
MongoDB: Role-Based Access Control
MongoDB Atlas uses role-based access control (RBAC) with optional field-level encryption:
- Define roles with specific permissions per collection
- Client-Side Field Level Encryption (CSFLE) for sensitive data
- API keys or connection strings for authentication
- Typically accessed through a backend API layer, not directly
Access Control
| Access Type | Supabase | MongoDB Atlas |
|---|---|---|
| Row/Document Level | Yes (RLS policies) | Limited (requires app logic) |
| Field Level | Via views or policies | Yes (CSFLE encryption) |
| Collection/Table Level | Yes | Yes |
| User-Based Access | auth.uid() in policies | Application layer |
Key Difference: Supabase lets you define per-row access rules in the database itself. MongoDB typically requires you to implement this logic in your application code or API layer.
Common Security Patterns
User Data Isolation
Both platforms can isolate user data, but the implementation differs:
Supabase: Create an RLS policy that checks auth.uid() = user_id on every query. This happens automatically at the database level.
MongoDB: Add a userId filter to every query in your API layer. You're responsible for ensuring this filter is always applied.
Field-Level Security
Supabase: Use database views or column-level policies to hide sensitive fields. Less common but possible.
MongoDB: Client-Side Field Level Encryption encrypts specific fields before they leave the application. Even database admins cannot read encrypted fields.
Encryption
| Encryption Type | Supabase | MongoDB Atlas |
|---|---|---|
| At Rest | Yes (managed by Supabase) | Yes (enabled by default) |
| In Transit | Yes (TLS) | Yes (TLS) |
| Field Level | Manual (pgcrypto) | Yes (CSFLE built-in) |
| Key Management | Vault integration possible | AWS KMS, Azure Key Vault, GCP KMS |
MongoDB Advantage: If you need to encrypt specific sensitive fields (like SSN or credit card numbers) while keeping other data queryable, MongoDB's CSFLE is more straightforward than Supabase's manual encryption approach.
Direct Client Access
Supabase is designed for direct frontend access with security handled by RLS. MongoDB Atlas typically requires a backend API:
- Supabase: Frontend talks directly to database, RLS filters results
- MongoDB: Frontend talks to your API, which talks to database
This means Supabase has a larger attack surface (direct database exposure) but also built-in protection (RLS). MongoDB relies on your API layer being secure.
Which Should You Choose?
Choose Supabase If:
You want built-in row-level access control, prefer SQL, need real-time subscriptions with security, or want to skip building a custom API layer. Great for apps where users own their data.
Choose MongoDB If:
You need flexible schemas, field-level encryption is critical, you're building a backend API anyway, or your data model is document-oriented. Better for complex nested data structures.
Is MongoDB less secure because it doesn't have RLS?
Not necessarily. MongoDB uses a different security model where access control typically happens in your application layer. This can be just as secure when implemented correctly, but requires more careful coding. Supabase's RLS provides security even if your application code has bugs.
Can I expose MongoDB directly to the frontend?
MongoDB Atlas provides Data API for direct access, but it lacks the fine-grained security of Supabase's RLS. For most applications, you should use a backend API layer with MongoDB to ensure proper access control.
Which is better for sensitive data like healthcare or finance?
MongoDB's Client-Side Field Level Encryption is excellent for highly sensitive fields that need encryption even from database admins. Supabase's RLS is great for access control but doesn't encrypt data at the field level. Consider your specific compliance requirements.
Can I migrate security settings between platforms?
No, security models are fundamentally different. Migrating from Supabase to MongoDB (or vice versa) requires rethinking and reimplementing your entire security strategy, not just moving data.