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Best Free & Open Source Alternatives to Auth0

Compare 4 open-source Auth0 alternatives including Keycloak, Authentik, SuperTokens and more

If you're looking for the best open-source alternative to Auth0, Keycloak is a strong place to start. If it doesn't quite fit your needs, there are plenty of other great options worth exploring, including Authentik, SuperTokens and Stack Auth. We've ranked the top alternatives to help you compare your options and find the right fit.

#1 Keycloak

Keycloak

Open-source identity and access management with SSO, OAuth2, OIDC, and SAML support for modern applications.

Keycloak is a battle-tested, open-source Identity and Access Management (IAM) solution maintained by Red Hat. It provides single sign-on (SSO), social login, user federation, and fine-grained authorisation out of the box — with support for standard protocols including OAuth 2.0, OpenID Connect (OIDC), and SAML 2.0.

Deployed as a standalone server, Keycloak manages users, roles, and client applications through a rich admin console. It supports external identity providers, LDAP/Active Directory federation, custom authentication flows, and multi-factor authentication — covering the full spectrum of enterprise identity needs.

Compared to Auth0 or Okta, Keycloak is entirely self-hosted and free, with no per-user pricing or usage caps. It is widely used in enterprises, cloud-native environments, and Kubernetes clusters (via the Keycloak Operator), making it the go-to open-source choice for organisations that want full control over their identity infrastructure.

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#2 Authentik

Authentik

Open source identity provider and SSO solution that replaces Auth0 and Okta with a self-hostable, flexible authentication platform.

Authentik is a versatile, open source identity provider that provides single sign-on, user enrollment, and authentication flows for modern applications. It is a popular self-hostable alternative to Auth0, Okta, and OneLogin for teams that want full control of their identity stack.

Authentik supports SAML, OAuth2, OpenID Connect, LDAP, RADIUS, and SCIM, and ships with a polished admin UI, configurable flows for passwordless login, MFA, passkeys, and social logins, and a powerful proxy provider for adding auth in front of legacy apps. It integrates natively with hundreds of services through a comprehensive provider catalog.

Released under an MIT-style license and built on Python and React, Authentik is widely used by small businesses, universities, and homelabbers that want an enterprise-grade identity provider without the per-user pricing of commercial IAM platforms.

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#3 SuperTokens

SuperTokens

Open-source authentication solution, an alternative to Auth0 and Firebase Auth that you can self-host.

SuperTokens is a comprehensive open-source authentication platform that lets you add secure login, session management, and user management to your application without the per-MAU pricing of Auth0 or Firebase Auth. It can be fully self-hosted or used via their managed cloud service.

SuperTokens supports email/password, passwordless (magic links and OTP), social OAuth (Google, GitHub, Apple, etc.), multi-factor authentication, and roles/permissions. It provides pre-built UI components and backend SDKs for Node.js, Python, Go, and more, with front-end support for React, Next.js, and Vanilla JS.

As a self-hosted solution, SuperTokens stores all user data in your own database (MySQL or PostgreSQL), giving you full data sovereignty. The open-source core is available under a permissive license for self-hosting, making it a popular choice for startups and enterprises looking to reduce authentication infrastructure costs.

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#4 Stack Auth

Stack Auth

Open-source authentication platform for Next.js and React, built as an alternative to Auth0 and Clerk.

Stack Auth is an open-source, self-hostable authentication and user management solution designed specifically for modern web apps built with Next.js and React. It is a developer-friendly alternative to Auth0 and Clerk, offering pre-built UI components, server and client SDKs, and a hosted dashboard.

It supports email/password login, magic links, OAuth social providers (Google, GitHub, Facebook, and more), session management, multi-tenant organizations, and role-based access control — all configurable with minimal code. Stack Auth ships with fully functional sign-in, sign-up, and account pages that you can drop into your Next.js app in minutes.

As an open-source project it can be self-hosted on your own infrastructure, giving you full control over user data. It is also available as a managed cloud service for teams that prefer a hosted option.

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Frequently Asked Questions

Are there any open source alternatives to Auth0?

Yes, there are 4 open source alternatives to Auth0. Popular options include Keycloak, Authentik, SuperTokens and more. These alternatives are free to use and many offer self-hosting options.

What is the best free alternative to Auth0?

The best free alternative to Auth0 depends on your specific needs. Keycloak is a popular choice with self-hosting capabilities. All alternatives listed here are open source and free to use.

Can I self-host an alternative to Auth0?

Yes, 4 of the alternatives listed here can be self-hosted, giving you complete control over your data and privacy.

Why should I switch from Auth0 to an open source alternative?

Open source alternatives to Auth0 offer several advantages: no vendor lock-in, complete data ownership, no subscription fees, the ability to self-host for privacy and security, and active community support. You can also customize the software to fit your specific needs.

Auth0

Auth0

Auth0 is a flexible, drop-in solution to add authentication and authorization services to your applications. It provides identity management, SSO, MFA, and social login for any platform.

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