Auth0

Auth0 is a flexible authentication and authorization platform that handles user login, registration, password resets, multi-factor authentication (MFA), and single sign-on (SSO) for web and mobile applications. With pre-built login UI components, SDKs for every major platform, and support for social logins, enterprise SSO, and passwordless authentication, Auth0 eliminates months of security development work while maintaining compliance with industry standards.

Best for: Development teams building B2B SaaS or B2C applications who want enterprise-grade authentication without building it from scratch. Particularly valuable for startups needing social login (Google, GitHub, Facebook) and teams supporting enterprise customers requiring SAML or AD/LDAP integration. Auth0's Universal Login handles the entire authentication flow with security best practices built-in.

Common Questions

What authentication methods does Auth0 support?
Auth0 supports username/password, passwordless (email magic links, SMS codes), social logins (Google, Facebook, GitHub, LinkedIn, 30+ providers), enterprise SSO (SAML, Active Directory, LDAP, Azure AD), and multi-factor authentication (SMS, authenticator apps, push notifications). Custom authentication via extensibility hooks lets you integrate with legacy systems or add custom validation logic.

How does Auth0 pricing work?
Auth0 uses a per-monthly-active-user (MAU) model. The Free tier includes 7,500 MAU with basic features. Essentials starts at $35/month for 500 MAU ($0.07/MAU after), adding custom domains and anomaly detection. Professional is $240/month for 500 MAU ($0.50/MAU after), with MFA and breached password detection. Enterprise has custom pricing with advanced features and support.

Does Auth0 work with mobile apps?
Yes, Auth0 has native SDKs for iOS (Swift), Android (Kotlin/Java), React Native, Flutter, and Xamarin. Mobile apps use secure OAuth 2.0 flows with native login experiences. Supports biometric authentication (Face ID, Touch ID, fingerprint), refresh tokens for persistent login, and offline token validation for apps that work without connectivity.

What is Universal Login?
Universal Login is Auth0's hosted login page that handles authentication flows (signup, login, password reset, MFA) with security best practices built-in. Instead of building login forms in your app, redirect users to Auth0's page, which is white-labeled with your branding. This centralizes security updates and ensures consistent authentication across web and mobile apps.

Pricing & Plans

• Free: 7,500 MAU, unlimited logins, social logins, 2 social connections, email support
• Essentials: $35/month base + $0.07/MAU (500 MAU included), custom domains, anomaly detection
• Professional: $240/month base + $0.50/MAU (500 MAU included), MFA, breached passwords, phone support
• Enterprise: Custom pricing, adds advanced MFA, DDoS protection, 99.99% SLA, TAM support

Additional MAU charged at tier rate. Volume discounts available for 100,000+ MAU.

Limitations

• MAU costs scale with growth: Applications with hundreds of thousands or millions of active users face significant monthly costs at $0.07-$0.50 per user, potentially exceeding $10,000+/month.
• Vendor lock-in complexity: Migrating away from Auth0 after building flows around their SDKs, Rules, and Actions requires substantial engineering work to rebuild authentication logic.
• Free tier limitations: The 2 social connection limit means you can't offer Google + GitHub + Facebook login simultaneously without upgrading to paid plans.

Getting Started

1. Sign up for free at auth0.com
2. Create a new application and select your platform (SPA, web app, mobile)
3. Configure allowed callback URLs and logout URLs
4. Install Auth0 SDK for your platform (npm, CocoaPods, Gradle, etc.)
5. Implement login button that redirects to Auth0's Universal Login
6. Handle the authentication callback to get user tokens
7. Customize Universal Login with your logo and brand colors
8. Enable social connections (Google, GitHub) or enterprise SAML from dashboard

The free tier is genuinely useful for development and small applications. Auth0's Quickstarts provide copy-paste code for most platforms.