SaaSpark Auth0's pricing tends to surprise teams as MAU grows. The three options below cover the spectrum: turnkey UX (**Clerk**), Google-scale free tier (**Firebase Auth**), or bundled with the rest of your backend (**Supabase**). Pick based on whether the cost driver is engineering time, MAU bill, or backend simplification.
Clerk
Drop-in authentication and user management for modern apps.
- Category: auth-identity
Why we picked it: Cleanest React/Next.js components and built-in org/multi-tenant primitives.
Firebase Auth
Multi-provider authentication tied to the Firebase platform.
- Category: auth-identity
Why we picked it: Free under 50K MAU and natural fit if you're already on Firebase.
Supabase
MCPOpen-source Firebase alternative with Postgres, auth, storage.
- Category: database-baas
Why we picked it: Auth bundled with Postgres + storage — useful when you'd otherwise pay for both separately.
How we selected these
Every tool in this ranking is in our catalog and has been verified by a human editor. We refresh pricing weekly and re-review the ranking quarterly. See our methodology for the full criteria.