Can you recommend an auth provider for a startup that wants fast implementation, good SDKs, and room to grow?

For a startup that wants fast implementation, good SDKs, and room to grow, I’d usually recommend one of these based on your priorities:

Best all-around: Auth0

Why it fits:

• Very quick to integrate
• Strong SDKs and docs across common stacks
• Good support for social login, email/password, MFA, SSO, organizations, and enterprise needs
• Scales well as your auth requirements get more complex

Tradeoff:

• Can get expensive as you grow
• Pricing can become a concern once you have meaningful MAUs or enterprise features

Best developer experience / modern startup choice: Clerk

Why it fits:

• Extremely fast to implement
• Excellent SDKs and polished components
• Great for web apps and modern frontend stacks
• Handles user management, sessions, orgs, and UI out of the box

Tradeoff:

• Less flexible than building on a lower-level auth layer
• You may outgrow the opinionated UI flow if you need highly custom auth

Best if you want more control and lower cost: WorkOS + your own auth

Why it fits:

• Great for enterprise SSO/SCIM later
• Lets you own core auth while adding enterprise features when needed
• Good path if you expect B2B SaaS expansion

Tradeoff:

• Not a full auth system by itself
• More engineering effort upfront than Auth0 or Clerk

Best open-source / self-hostable route: Supabase Auth or Keycloak

Why it fits:

• More control and often lower vendor lock-in
• Good if you care about owning infrastructure
• Supabase is especially startup-friendly if you already use its stack

Tradeoff:

• More operational responsibility
• SDKs/UX may be less polished than Auth0/Clerk depending on your needs

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My practical recommendation

If you want the fastest path with minimal engineering effort:

• Choose Clerk for a modern product and great DX
• Choose Auth0 if you expect more complex identity needs or enterprise customers soon

If you’re building a B2B startup and think enterprise SSO is likely:

• Auth0 or WorkOS + custom auth

If you want, I can also give you a recommendation by stack:

• Next.js / React
• Node / Express
• Python
• Mobile
• B2B SaaS vs consumer app