Supabase vs Firebase Security: Complete 2026 Comparison

Security Overview

Both Supabase and Firebase are popular Backend-as-a-Service (BaaS) platforms that handle authentication, databases, and storage. However, they take fundamentally different approaches to security that have significant implications for how you build and protect your applications.

Supabase uses PostgreSQL with Row Level Security (RLS) policies written in SQL. This gives you granular, database-level control over who can access what data.

Firebase uses Firestore Security Rules, a custom DSL (domain-specific language) that defines access patterns. Rules are evaluated on the server before any read or write operation.

Data Access Control: RLS vs Firestore Rules

Supabase Row Level Security (RLS)

Supabase leverages PostgreSQL's native Row Level Security feature. RLS policies are SQL expressions that determine whether a row can be accessed or modified.

Example: Users can only read their own data

-- Enable RLS on the table
ALTER TABLE profiles ENABLE ROW LEVEL SECURITY;

-- Create policy for SELECT
CREATE POLICY "Users can view own profile"
ON profiles FOR SELECT
USING (auth.uid() = user_id);

-- Create policy for UPDATE
CREATE POLICY "Users can update own profile"
ON profiles FOR UPDATE
USING (auth.uid() = user_id)
WITH CHECK (auth.uid() = user_id);

Advantages of RLS:

• Enforced at the database level - impossible to bypass from application code
• Uses standard SQL - familiar syntax for developers
• Can reference other tables and use complex joins
• Policies are version-controlled with your schema migrations

Firebase Firestore Security Rules

Firebase uses a custom rules language that's evaluated on Google's servers before any operation.

Example: Users can only read their own data

rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
    match /profiles/{userId} {
      allow read, write: if request.auth != null 
                         && request.auth.uid == userId;
    }
  }
}

Advantages of Firestore Rules:

• Simpler syntax for basic use cases
• Integrated testing tools in Firebase console
• Rules can validate data structure and content
• Good documentation and examples

API Key Management

Supabase API Keys

Supabase uses two primary API keys:

• Anon Key (Public) - Safe to expose in client-side code. Respects RLS policies. This is your default key for browser/mobile apps.
• Service Role Key (Secret) - Bypasses all RLS policies. Should NEVER be exposed in client code. Use only in trusted server environments.

Firebase API Keys

Firebase takes a different approach:

• API Key - Primarily used for identification, not authentication. Safe to expose publicly.
• Service Account Key - Full admin access. Should never be exposed client-side.

Firebase's API key is less sensitive than Supabase's because it relies on Security Rules (not the key) to control access. However, this can lead to a false sense of security - if your rules are misconfigured, the exposed API key becomes a gateway to your data.

Authentication Security

Both platforms provide robust authentication options. The main difference is in how auth state integrates with data access:

• Supabase: Uses auth.uid() function in RLS policies. The JWT is passed with every request and verified server-side.
• Firebase: Uses request.auth object in security rules. Auth state is automatically managed by the SDK.

Common Vulnerabilities

Supabase Common Mistakes

1. RLS not enabled - Tables are publicly accessible by default
2. Service role key exposed - Grants full database access
3. Missing WITH CHECK clause - Allows inserting data that can't be read back
4. Overly permissive policies - Using USING (true) defeats the purpose
5. Forgetting to secure storage buckets - File access has separate RLS

Use our Security Checklist to audit your Supabase project for these vulnerabilities.

Firebase Common Mistakes

1. Test-mode rules in production - allow read, write: if true
2. Not validating data structure - Allowing arbitrary fields to be written
3. Recursive rules not considered - Complex nested documents with inconsistent access
4. No rate limiting - Rules don't prevent abuse/spam
5. Realtime Database vs Firestore confusion - Different rule syntax and behavior

Side-by-Side Security Comparison

Final Verdict

The most important factor isn't which platform you choose - it's whether you properly configure security before going to production. Both platforms have dangerous defaults that can expose your data if you're not careful.

Related Resources

• Supabase Security Best Practices Guide
• Anon Key vs Service Key Explained
• 25+ RLS Policy Patterns
• Supabase vs PlanetScale Security