What authentication service should I use for a mobile app and web dashboard?

For a mobile app + web dashboard, the best general choice is usually an OAuth 2.0 / OpenID Connect (OIDC) authentication provider that supports:

• Mobile SDKs (iOS/Android)
• Web login flows
• Social login if needed
• MFA / passwordless
• User management
• Custom roles/permissions
• JWT access tokens / refresh tokens

Good options by use case

Best overall for most teams

• Auth0
  Great developer experience, strong support for mobile + web, lots of integrations.
  Best if you want to move fast and don’t mind higher cost.

Best if you want managed, simpler, and often cheaper

• Firebase Authentication
  Good for apps already using Firebase/Google Cloud.
  Easier to set up, strong for mobile, decent for web.
  Less flexible for complex enterprise auth.

Best if you want full control / open source

• Keycloak
  Powerful and self-hosted. Good for custom enterprise needs, but more setup and maintenance.

Best AWS-native option

• AWS Cognito
  Works well if your backend is on AWS. Can be clunky, but cost-effective and scalable.

Best if your app is already in the Microsoft ecosystem

• Azure AD B2C / Microsoft Entra External ID
  Strong for enterprise/customer identity scenarios.

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My practical recommendation

• Startup / SaaS / fastest launch: Auth0
• Firebase-based mobile app: Firebase Auth
• Need self-hosting or more control: Keycloak
• Already on AWS: Cognito

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What to look for

Make sure the service supports:

• OIDC/OAuth2
• PKCE for mobile/web
• Refresh token rotation
• MFA
• Role-based access control
• Secure session management
• Good SDKs for React Native / Flutter / iOS / Android / React/Vue/Next.js

If you tell me:

1. your tech stack,
2. whether you need social login or enterprise SSO,
3. whether you want hosted vs self-hosted,

…I can recommend the best specific service for your app.