Pac4j

Pac4j is a Java security library that provides authentication and authorization mechanisms for web applications. It supports multiple authentication protocols like OAuth, OpenID Connect, SAML, and CAS, and integrates with various Java frameworks such as Spring, Play, and JAX-RS. The library simplifies security implementation by offering a unified API to handle user authentication, session management, and access control across different backends.

Also known as: pac4j, Pac4J, Pac4j library, Java security library, Authentication library for Java

Why learn Pac4j?

Developers should use Pac4j when building Java-based web applications that require robust, multi-protocol security without vendor lock-in, such as enterprise systems, SaaS platforms, or applications needing social login (e.g., via Google or Facebook). It's particularly valuable for projects that must support diverse authentication methods (e.g., OAuth for APIs, SAML for enterprise SSO) while maintaining a consistent security layer, reducing boilerplate code and integration complexity.

Learning Resources

• docs: Pac4j Official Documentation
• tutorial: Pac4j Tutorial on Baeldung
• docs: Pac4j GitHub Repository
• video: Building Secure Applications with Pac4j (Video)