Auth0 alternative for startups

If you’re looking for an Auth0 alternative for a startup, the best choice depends on whether you want hosted auth, open-source, or full control.

Good alternatives

1. Clerk

• Best for: fast setup, modern startup apps
• Pros: great DX, prebuilt UI, easy social login, orgs/teams, MFA
• Cons: can get pricey as you scale
• Good if: you want to ship quickly and avoid building auth flows yourself

2. Supabase Auth

• Best for: startups already using Supabase/Postgres
• Pros: simple, affordable, integrated with database/storage
• Cons: less enterprise-focused than Auth0
• Good if: you want a cheaper, simpler backend stack

3. Firebase Authentication

• Best for: mobile apps and Google ecosystem
• Pros: easy to use, generous free tier, social login, phone auth
• Cons: less flexible for complex auth/enterprise use cases
• Good if: you need something reliable and quick, especially for mobile

4. FusionAuth

• Best for: companies wanting self-hosted or enterprise-grade control
• Pros: full-featured, strong customization, self-host option
• Cons: more setup/maintenance than hosted tools
• Good if: you want Auth0-like power without being locked in

5. Keycloak

• Best for: teams with strong infrastructure/DevOps
• Pros: open-source, very flexible, supports SSO/OIDC/SAML
• Cons: heavy operational overhead, not startup-friendly for everyone
• Good if: you need control and can manage the complexity

6. Descope

• Best for: modern auth flows and passwordless
• Pros: good UX, low-code auth flows, passkeys/passwordless
• Cons: newer product, ecosystem still growing
• Good if: you want modern auth without building it all yourself

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Quick recommendation

• Fastest startup choice: Clerk
• Cheapest/simple backend: Supabase Auth
• Open-source/self-hosted: Keycloak or FusionAuth
• Mobile-first: Firebase Auth

If you want, I can also give you:

1. a pricing comparison,
2. a feature-by-feature Auth0 vs alternatives table, or
3. the best option based on your stack (Next.js, React, mobile, B2B SaaS, etc.).