Auth0

Auth0, now part of the Okta Identity Platform, is a developer-first identity and access management solution that abstracts away the enormous complexity of building authentication systems from scratch. Instead of spending months implementing secure login flows, multi-factor authentication, social login, and user management, development teams can integrate Auth0 in days and focus their engineering effort on building their actual product.

Auth0 supports virtually every authentication method in use today: username and password, social logins through Google, Facebook, Apple, GitHub and dozens more, enterprise SSO via SAML and OpenID Connect, passwordless authentication via email or SMS codes, and biometric login. The Universal Login page is customizable and handles the security-critical authentication flow on Auth0's hardened infrastructure, reducing your application's attack surface.

The developer experience is Auth0's key differentiator in the identity management space. SDKs are available for every major platform and framework — React, Angular, Vue, Next.js, Express, Django, Spring, and many more. The documentation is consistently praised as among the best in the developer tools space, with clear guides, practical code samples, and interactive tutorials that make integration straightforward even for complex enterprise scenarios.

For enterprise SaaS deployments, Auth0 provides Organizations, a feature that enables multi-tenant B2B applications to manage separate authentication policies per customer. This is critical for SaaS companies whose enterprise clients require their own identity provider connections, custom MFA policies, and independent user management dashboards.

The free plan is generous for development and small applications, supporting up to 25,000 monthly active users with unlimited social connections at no cost. This makes it practical for startups and side projects without any upfront investment. Paid plans start at 23 USD per month for enhanced features including advanced MFA, custom domains, and higher usage limits.

Auth0 Actions allow developers to insert custom logic into the authentication pipeline — adding claims to tokens, calling external APIs, enforcing geographic access policies, or implementing progressive profiling. This extensibility makes Auth0 suitable for complex identity use cases without sacrificing the convenience of a fully managed platform.