Should I use Clerk or Auth0?
For a new startup in 2026, use Clerk. It's modern, opinionated, secure-by-default, and priced for startups. Auth0 is still a great enterprise choice but has more surface area to misconfigure and a steeper pricing curve. Migrate to Auth0 if Clerk specifically can't scale to your needs.
Quick comparison:
**Clerk** - Modern API, ergonomic React SDKs - Sensible defaults (MFA, passkey, OAuth) - Free tier up to 10K MAUs - Pricing scales cleanly - Smaller team = faster feature velocity
**Auth0** - Enterprise-grade feature set - More complex (rules, actions, flows) - Free tier up to 25K MAUs - Pricing gets expensive above 25K - Ex-Okta acquisition means roadmap changes
Security posture — both are secure by default; both have had vulnerabilities historically. Clerk's smaller surface area means fewer configuration mistakes; Auth0's depth means more ways to misconfigure.
For a 2026 AI-built app: Clerk. Specifically: - clerkMiddleware with a clear matcher - auth() called in every Server Action - Webhooks verified with svix signature - Never ship the secret key client-side
Migrating from Auth0 → Clerk later is a real project but tractable. Migrating Clerk → Auth0 is a real project but rare (usually enterprise-feature-driven).