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Keycloak vs. Auth0, a Open-Source Alternative

· 6 min read
Phase Two

Exploring Keycloak as an Alternative to Auth0 for Authentication Solutions

When it comes to implementing authentication and authorization in web applications, Auth0 and Keycloak are two prominent solutions that offer robust security features. While Auth0 is a popular choice for many developers due to its comprehensive, cloud-based platform, Keycloak presents a compelling alternative, especially in terms of cost and flexibility. This blog post will delve into how Keycloak stacks up against Auth0, focusing on cost of ownership, maintenance, and functionality.

Cost of Ownership

There are many factors to think about with a total cost-of-ownership. We've written extensively about choosing an Open-Source IAM over a managed service.

Auth0: Auth0 operates on a subscription model, which can be quite enticing for startups or small projects with minimal authentication needs. It offers a free tier limited by the number of authentications per month, active users, MFA setups, and more. As needs quickly increase for a business to setup a modest number of IDP connections, include minimal additional "users" (which could be people or devices), extract logs, customize deployments, and more, those bills can quickly spiral into $100K+. For SMB's to Enterprise, dedicating that amount of resources to your Auth solution can be untenable.

Keycloak: Keycloak, on the other hand, is an open-source solution developed by Red Hat. It is free to use, regardless of the number of users or the scale of the project. This makes Keycloak particularly attractive for businesses looking to cut costs or those who prefer not to be tied to vendor-specific pricing structures. The primary cost associated with Keycloak comes from the need to self-host and manage the software, which includes server costs and potential overhead for setup and maintenance. This can mean the ongoing cost is fixed since its not driven by features or users.



Leveraging Phase Two's managed hosting provides a more capable free tier to test out and integrate Authorization and Authentication into an application(s). When that application's needs grow, Keycloak quickly becomes a far more cost-effective choice.


Auth0: One of the main advantages of Auth0 is that being a managed service, it requires minimal maintenance from the user's side. The Auth0 team handles updates, security patches, and infrastructure, ensuring that the system is kept up-to-date.

Keycloak: Conversely, Keycloak requires more attention since it's self-hosted. Organizations must allocate resources for installing, configuring, and updating the software, as well as managing the underlying infrastructure. This can be a drawback for teams without the necessary technical expertise or resources. However, it also offers greater control over the deployment and security standards, which can be a significant advantage for certain regulatory environments.



As a fully managed service, Auth0 abstracts away this work.

Functionality and Flexibility

Auth0: Auth0 offers a wide range of authentication features out-of-the-box, including social logins, enterprise federation, database connections, and more. It supports a variety of standards like OAuth2, OpenID Connect, and SAML, making it highly versatile for modern web applications. The platform also provides robust analytics and real-time monitoring tools that can be crucial for understanding user behavior and mitigating potential security threats.

Keycloak: Keycloak matches Auth0 in terms of functionality, supporting similar authentication protocols and user federation. It also offers customizable user interfaces for login, registration, and account management, which can be tailored to match the specific needs of a business. Being open-source, Keycloak allows developers to modify the codebase and integrate with other systems more freely than Auth0, offering a higher degree of customization at the cost of additional developer effort.

A key feature of keycloak is it's ability to be hosted on-premise in a variety of ways. This means that as you choose to deploy something within your own systems, you'll be able to do this with Keycloak. If your requirements include an on-premise solution, learn more about this how Keycloak can help with user management and identity brokering for on-premise.



Auth0 and Keycloak offer much of the same functionality for Authentication and Authorization, however Keycloak is extremely flexible to extend and configure. It's a system that can adjust and grow with an application. Lastly, the ability to host Keycloak on-premise makes it a strong option for companies.

Integrating Keycloak with External Systems like Auth0

For organizations looking to transition from Auth0 to Keycloak or integrate Keycloak with systems that are already using Auth0, Keycloak's flexibility offers significant advantages. Keycloak can be configured to act as a broker that sits between Auth0 and your applications. This setup allows organizations to leverage the strengths of both platforms. For example, an organization can use Auth0 for external user management due to its robust third-party integrations while using Keycloak to handle more sensitive internal authentication needs.

The identity brokering capability of Keycloak enables it to delegate authentication to external Identity Providers (IdPs), such as Auth0. This means that Keycloak can manage internal permissions and roles, provide additional security checks, and maintain a user-friendly, consistent login experience across different systems. The ability to integrate seamlessly with services like Auth0 simplifies the migration process for companies transitioning from one authentication system to another and provides a layer of flexibility for new authentication strategies without disrupting user access or security.

Which One Is Best for Me?

Choosing between Auth0 and Keycloak largely depends on your organization’s specific needs and capabilities. Auth0 is an excellent choice for those who need a fully managed solution with costs linked to user numbers and features. However, for organizations that prioritize cost savings and predictability, have the capability to manage their infrastructure, or require extensive customization, Keycloak emerges as a powerful, budget-friendly alternative.

Both platforms offer extensive documentation and community support, which can help mitigate some of the challenges associated with implementation and maintenance.

Ultimately, we at Phase Two believe marrying the two together is the strongest match. We offer robust hosting options that fit well for multiple business sizes. Coupling the capabilities of Keycloak and the advantages of a managed service translates directly to implementation and cost control. Leveraging Keycloak means that ongoing costs are relatively fixed, since concerns about user growth or feature needs don't have to factor into every decision.