The best open source alternative to Auth0 is Keycloak, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to Auth0 and 12 is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Auth0 are Ory (Free, Open Source), Gluu Server (Freemium, Open Source), IdentityServer (Freemium, Open Source) and Authelia (Free, Open Source).
Ory builds cloud-native authentication (login), authorization (permission), delegation (OAuth2, OpenID Connect), and user management software. You can deploy what you need yourself or use the Ory Cloud Platform and get started in minutes.
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Ory vs Auth0 opinions
pros, cons and recent comments
vinckr It is a truly free and open alternative and is built with a modern architecture in mind.
An open-source, standards-compliant, and flexible OpenID Connect and OAuth 2.0 framework for ASP.NET Core. - Single sign-on for for applications - Supports applications developed for the web, mobile, desktops, devices, and more.
Pomerium is an identity-aware proxy that enables secure access to internal applications. Pomerium provides a standardized interface to add access control to applications regardless of whether the application itself has authorization or authentication baked-in.
FreeRADIUS is responsible for authenticating one third of all users on the Internet. Welcome to the FreeRADIUS project, the open source implementation of RADIUS, an IETF protocol for AAA (Authorisation, Authentication, and Accounting).