CAS (Central Authentication Service)

Name: CAS (Central Authentication Service)
Brand: CAS (Central Authentication Service)
Availability: InStock

Identity and Access Management (IAM)

Open Source

Free Tier

Self-hosted

OpenMSP Score

Reddit Impact Score

Github Score

729M

11KStars

3KForks

32KCommits

Apache License 2.0License

Mar 21, 2026Last commit

Alternative Vendors

Keycloak

Teleport

Authentik

Commercial Alternatives

Okta

Azure Active Directory

Huntress

Duo Security

CAS (Central Authentication Service) is an open-source single sign-on protocol for web applications. It provides centralized authentication and authorization services with support for various authentication methods and integration with existing identity systems.

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Key Features

Enterprise Single Sign-On Protocol

Implements CAS v1, v2, v3, SAML v1/v2, OAuth v2, OpenID Connect, and WS-Federation protocols for comprehensive SSO support across multiple applications and platforms

Multi-Authentication Support

Supports authentication via JAAS, LDAP, RDBMS, X.509, RADIUS, SPNEGO, JWT, MongoDB, Apache Cassandra, and social providers like WS-FED, SAML2, OpenID Connect

High Availability Clustering

Built-in support for HA clustered deployments using Hazelcast, JPA, Memcached, Apache Ignite, MongoDB, Redis, and DynamoDB for enterprise-scale reliability

Multi-Factor Authentication

Comprehensive MFA support including Duo Security, YubiKey, RSA, Google Authenticator (TOTP), WebAuthn FIDO2, and other modern authentication methods

Pros and Cons

Pros

Open Source and Free

100% free open source software licensed under Apache v2, managed by Apereo Foundation with no licensing costs

Extensive Protocol Support

Supports virtually all modern authentication protocols including SAML, OAuth, OpenID Connect, and legacy systems

Enterprise-Grade Scalability

Proven to scale from small deployments to Fortune 500 companies with clustering and high availability features

Cons

Complex Configuration

Requires significant technical expertise to configure and deploy properly, especially for advanced features

Limited Commercial Support

Relies primarily on community support; commercial support options are limited compared to proprietary solutions

Feature Comparison

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