Auth0 vs Keycloak

Auth0 is a customer identity and access management (CIAM) platform that developers use to add login, sign-up and authorization to their applications. Founded in 2013, it was acquired by Okta in 2021 and now operates as Okta's customer identity product, alongside Okta's workforce identity business. Its job is to handle authentication so product teams do not build password storage, MFA and SSO themselves.

The platform centers on Universal Login, a hosted login page that supports social providers, enterprise connections (SAML, OIDC, Active Directory), passwordless email and SMS, passkeys and multi-factor authentication. Organizations support B2B multi-tenancy where each customer brings its own identity provider, Actions let teams run custom code in login and registration flows, and Fine-Grained Authorization handles relationship-based permissions. Attack protection covers bot detection, breached password checks and brute-force limits. The free plan was expanded in 2024 to 25,000 monthly active users; paid tiers are priced by MAU and features, and enterprise connections push buyers into higher plans quickly.

Auth0 fits B2B SaaS companies selling to enterprises that demand SSO, and consumer apps with large user bases and compliance requirements. It is less attractive for small teams that want drop-in UI components and predictable pricing: Clerk is simpler for React and Next.js apps, while Keycloak and Better Auth give full ownership without per-user fees.

Keycloak is an open-source identity and access management server, originally created by Red Hat and now a Cloud Native Computing Foundation (CNCF) incubating project under the Apache 2.0 license. It provides single sign-on for web and mobile applications and APIs using the standard OpenID Connect, OAuth 2.0 and SAML 2.0 protocols, and it runs on your own infrastructure.

Its feature set matches commercial identity products: user federation with LDAP and Active Directory, identity brokering with social logins and external identity providers, multi-factor authentication with OTP and WebAuthn, password policies, fine-grained authorization services, realms for multi-tenancy, an admin console and a self-service account console. Login pages and emails can be themed, and extensions are written in Java through service provider interfaces. The software is free; Red Hat sells a supported distribution, the Red Hat build of Keycloak, for organizations that need commercial support.

Keycloak fits enterprises, public institutions and B2B software vendors that need to keep identity data under their own control, for example for data residency or regulatory reasons. The trade-off is operational: running it in high availability, tuning databases and caches, upgrading between major versions and customizing themes require expertise. Startups that want hosted authentication with polished UI components usually choose Auth0, Clerk or WorkOS, while Authentik and Zitadel are newer open-source alternatives with lighter operations.