Modern applications require secure authentication, authorization, and user management. Instead of relying on SaaS tools like Auth0 or Okta, many organizations are adopting open-source IAM solutions for flexibility, cost control, and data ownership.
In this blog, we’ll explore:
- Keycloak
- WSO2 Identity Server
- Apereo CAS
- SuperTokens
- Authentik
Most modern IAM tools support self-hosted, cloud, and hybrid deployments
What is Single Sign-On (SSO)?
Single Sign-On (SSO) is an authentication method that allows a user to log in once and access multiple applications without logging in again.
Simple Example
Think of logging into Google:
- You si
- Then you can open YouTube, Google Drive, or Docs
- No need to log in again
That’s SSO in action.
What is Self-Hosted IAM?
Self-hosted IAM means:
- You run the identity system on your own infrastructure
(VMs, Kubernetes, Docker, on-prem, or cloud) - You control:
- User data
- Security policies
- Scaling & uptime
Almost all open-source IAM tools allow deployment:
- On-premise
- Cloud (AWS, Azure, GCP)
- Containers (Docker/K8s)
Keycloak – Self-Hosted Enterprise Standard
Keycloak is one of the most popular open-source IAM tools, originally backed by Red Hat and now part of CNCF.
Key Features
- SSO (Single Sign-On)
- OAuth2, OpenID Connect, SAML support
- Social login & identity brokering
- LDAP / Active Directory integration
- MFA support
Self-Hosted Support
- Docker / Kubernetes ready
- On-prem & cloud deployment
- Full control over authentication flows
It can run anywhere with JVM support
Pricing
- Free & open-source
- Paid support via Red Hat
Best For
Complex authentication (SSO, federation, MFA)
Enterprises
Pros
- Mature ecosystem
- Enterprise features
- Strong community
Cons
- Heavy and complex to manage
Link
WSO2 Identity Server (Enterprise IAM Platform)
Overview
WSO2 Identity Server is a fully-fledged enterprise IAM solution with deep identity federation and API security.
Key Features
- Advanced SSO & federation
- API security integration
- Identity governance
- Adaptive authentication
- SCIM provisioning
Self-Hosted Support
- Fully deployable on-premise
- Kubernetes & cloud-native setups
- Hybrid deployments
Pricing
- Open source (Apache 2.0)
- Enterprise subscription (support + cloud)
Pros
- Highly customizable
- Strong for large enterprises
Cons
- Steep learning curve
- Complex deployment
Link
Apereo CAS (Classic SSO System)
Overview
Apereo CAS is one of the oldest SSO solutions, widely used in universities and enterprises.
Key Features
- Central Authentication (SSO)
- Supports SAML, OAuth, OpenID
- Strong protocol compatibility
- Lightweight compared to Keycloak
Self-Hosted Support
- Designed primarily for on-prem/self-hosted
- Lightweight deployment
Pricing
- 100% Free & Open Source
- No official paid SaaS (community-driven)
Pros
- Very stable
- Lightweight
Cons
- UI and developer experience outdated
- Less modern features compared to newer tools
Link
SuperTokens (Developer-First Auth)
SuperTokens is a modern, developer-friendly authentication solution.
Key Features
- Passwordless login
- Session management
- Social login
- Modular architecture (frontend + backend SDKs)
- API-first design
Self-Hosted Support
- Backend can be fully self-hosted
- Works with your own database
- API-first architecture
Designed for developers building custom auth flows
Pricing
- Free open-source core
- Paid features:
- Multi-tenancy
- Enterprise SSO
- MFA
Pros
- Easy to integrate
- Lightweight
- Flexible
Cons
- Fewer enterprise features than Keycloak
Link
Authentik (Modern & Lightweight IAM)
Overview
Authentik is a modern alternative to Keycloak, focused on simplicity and usability.
Key Features
- SSO with OIDC & SAML
- Policy-based access control
- Proxy-based authentication
- Docker-first deployment
Self-Hosted Support
- Docker-first deployment
- Kubernetes support
- Reverse proxy authentication
Popular in self-hosted/homelab communities
Pricing
- Fully open source
- Optional enterprise support
Pros
- Lightweight
- Easy to deploy
- Modern UI
Cons
- Smaller ecosystem
- Less enterprise maturity
Link
Comparison Summary
| Feature | Keycloak | WSO2 | CAS | SuperTokens | Authentik |
|---|---|---|---|---|---|
| Open Source | Yes | Yes | Yes | Yes (core) | Yes |
| Ease of Use | Complex | Complex | Medium | Easy | Easy |
| Enterprise Ready | Yes | Yes | ⚠️ | ⚠️ | ⚠️ |
| Protocol Support | ⭐⭐⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐ | ⭐⭐⭐⭐ |
| Customization | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐⭐ |
| Best For | Large enterprises | Enterprise IAM | Legacy SSO | Developers | SMB / modern apps |