Auth0
Cloud-based identity management platform for adding user authentication and authorization to applications
Apereo CAS
Enterprise Single Sign-On and Identity Provider for Web
Open-source Java-based authentication server supporting CAS, SAML2, OAuth2, OpenID Connect, and multifactor authentication with extensive integration options for enterprise identity management.
Overview
Enterprise Authentication Platform
Central Authentication Service (CAS) is a comprehensive, multilingual identity provider and single sign-on solution designed for enterprise web environments. Built on Spring Boot and Spring Cloud, CAS serves as a robust authentication server implementing multiple industry-standard protocols including CAS v1-v3, SAML v1/v2, OAuth v2, OpenID Connect, and WS-Federation.
Flexible Integration & Deployment
CAS supports authentication against virtually any identity source—LDAP, RDBMS, JAAS, X.509, RADIUS, SPNEGO, JWT, MongoDB, Apache Cassandra, and more. It enables delegated authentication to external providers, implements multifactor authentication through Duo Security, YubiKey, Google Authenticator, WebAuthn FIDO2, and other methods, and offers high-availability clustering via Hazelcast, Redis, MongoDB, DynamoDB, and additional backends.
Administration & Customization
The platform includes administrative interfaces for logging, monitoring, and configuration management, supports application registration through multiple backends (JSON, LDAP, YAML, JPA, cloud services), and provides per-application theming, password management, user consent workflows, and authorization via ABAC, OPA, OpenFGA, and Grouper. Deployment options include Apache Tomcat, Jetty, Undertow, and Docker containers, with the recommended WAR Overlay method for production installations.
Highlights
Multi-protocol support: CAS, SAML2, OAuth2, OpenID Connect, WS-Federation
Extensive authentication backends including LDAP, RDBMS, X.509, RADIUS, and social providers
Built-in MFA with Duo Security, YubiKey, Google Authenticator, WebAuthn FIDO2
High-availability clustering with Redis, Hazelcast, MongoDB, DynamoDB, and more
Pros
- Comprehensive protocol support covers most enterprise SSO requirements
- Highly extensible with pluggable authentication, authorization, and storage backends
- Active community with extensive documentation and regular releases
- Built on proven Spring Boot and Spring Cloud frameworks
Considerations
- Java-based deployment requires JVM expertise and infrastructure
- Complex configuration surface area due to extensive feature set
- WAR Overlay deployment model may be unfamiliar to modern DevOps teams
- Large codebase and dependencies can increase maintenance overhead
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When teams consider Apereo CAS, these hosted platforms usually appear on the same shortlist.
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Fit guide
Great for
- Enterprises requiring centralized SSO across heterogeneous applications
- Organizations needing SAML2 or OpenID Connect identity provider capabilities
- Environments with complex authentication requirements and multiple identity sources
- Teams seeking open-source alternatives to commercial IAM solutions
Not ideal when
- Small projects needing lightweight authentication without protocol complexity
- Teams without Java or Spring framework experience
- Greenfield microservices architectures preferring cloud-native identity solutions
- Organizations requiring turnkey SaaS identity management without self-hosting
How teams use it
University Campus SSO
Students and faculty authenticate once to access learning management systems, email, library resources, and administrative portals using LDAP credentials with MFA enforcement.
Enterprise SAML Identity Provider
Centralized identity provider federating access to SaaS applications like Salesforce, Google Workspace, and AWS Console using SAML2 with role-based authorization.
Multi-Protocol API Gateway Authentication
Legacy applications use CAS protocol while modern services authenticate via OAuth2/OpenID Connect, all managed through a single identity platform with Redis session clustering.
Healthcare System Access Management
Clinicians access EHR systems with X.509 certificate authentication, administrative staff use LDAP credentials, and external partners authenticate via federated SAML2 providers.
Tech snapshot
Java91%
JavaScript5%
HTML2%
Shell1%
Groovy1%
PHP1%
Frequently asked questions
What deployment method is recommended for production?
The WAR Overlay method is recommended. This approach allows you to customize CAS without cloning the entire codebase, making upgrades and maintenance easier.
Does CAS support multifactor authentication?
Yes, CAS supports multiple MFA providers including Duo Security, YubiKey, Google Authenticator, RSA, WebAuthn FIDO2, and a built-in Simple MFA option.
Can CAS integrate with existing LDAP or Active Directory?
Yes, CAS provides native LDAP authentication support and can authenticate users against Active Directory, OpenLDAP, and other LDAP-compliant directories.
What protocols does CAS support for single sign-on?
CAS supports its native CAS protocol (v1-v3), SAML v1/v2, OAuth v2, OpenID Connect, and WS-Federation Passive Requester Protocol for comprehensive SSO coverage.
How does CAS handle high availability and clustering?
CAS supports clustered deployments using ticket registries backed by Hazelcast, Redis, Memcached, MongoDB, DynamoDb, Apache Ignite, JPA, and other distributed storage systems.
Project at a glance
Active- Stars
- 11,296
- Watchers
- 11,296
- Forks
- 3,960
LicenseApache-2.0
Repo age14 years old
Last commit21 hours ago
Primary languageJava
Last synced 4 hours ago