Cas
by apereo
Enterprise-Grade Single Sign-On & Identity Management
Open-source authentication server supporting OAuth2, SAML, OpenID Connect, and multi-factor authentication for centralized access control.
- 11,281+ GitHub stars
- Built with Java
- Multi-protocol support including OAuth2, SAML2, OpenID Connect, and CAS protocol
- Apache License 2.0 license
About This Project
Apereo CAS is a comprehensive, battle-tested authentication and authorization platform that centralizes identity management across your entire application ecosystem. Built on Spring Boot and Spring Framework, it provides a robust foundation for implementing single sign-on (SSO) capabilities that work seamlessly with legacy systems and modern cloud applications alike.
Solve complex authentication challenges with built-in support for multiple protocols including OAuth2, SAML2, and OpenID Connect. Whether you're securing enterprise applications, educational platforms, or SaaS products, CAS handles everything from basic username/password authentication to sophisticated multi-factor authentication flows with Duo Security, FIDO2, and other modern MFA providers.
The platform's extensible architecture allows developers to integrate with virtually any identity source—LDAP directories, databases, REST APIs, or cloud identity providers like AWS. Its plugin-based design means you can customize authentication flows, add new protocols, or integrate with third-party services without modifying core code.
With over 11,000 GitHub stars and active development by the Apereo Foundation, CAS powers authentication for universities, government agencies, and enterprises worldwide. The project includes comprehensive documentation, Docker support, and a vibrant community that ensures long-term reliability and continuous innovation.
Key Features
- Multi-protocol support including OAuth2, SAML2, OpenID Connect, and CAS protocol
- Comprehensive MFA options with Duo Security, FIDO2, TOTP, and SMS authentication
- Flexible identity source integration including LDAP, Active Directory, databases, and REST APIs
- Spring Boot-based architecture with extensive customization through plugins and overlays
- Cloud-ready deployment with Docker support and AWS integration
- Delegated authentication and attribute release with fine-grained access policies
- Service registry management for controlling application access and protocol settings
- Built-in monitoring, auditing, and security event tracking capabilities
How You Can Use It
Implementing enterprise-wide SSO across web applications, mobile apps, and legacy systems
Building secure authentication for educational institutions with LDAP and Shibboleth integration
Adding multi-factor authentication to protect sensitive applications and APIs
Creating a centralized identity provider for microservices architectures using OAuth2/OIDC
Migrating from proprietary authentication systems to an open-source, standards-based solution
Federating authentication across multiple organizations using SAML2
Who Is This For?
Enterprise architects, security engineers, and Java developers responsible for authentication infrastructure in organizations requiring centralized identity management and SSO capabilities