Best Open Source SSO Providers in 2025: Keycloak vs Authentik vs Zitadel
- Philip Moses
- Nov 12
- 3 min read
Updated: Nov 19
In 2025, managing user logins and access across different applications has become one of the biggest challenges for businesses. That’s where Single Sign-On (SSO) comes in — it lets users log in once and access everything securely.
In this blog, we’ll look at the top 3 open source SSO providers in 2025 — Keycloak, Authentik, and Zitadel, compare their features, and help you decide which one fits your needs best.
What is Single Sign-On (SSO)?
Single Sign-On (SSO) allows users to access multiple applications using just one set of login details. Instead of remembering different passwords for every app, users log in once and get access to all connected services.
SSO improves:
User experience — fewer logins, less hassle
Security — centralized authentication and control
Efficiency — simpler management for IT teams
Why Use Open Source SSO Providers in 2025?
Open source SSO tools are gaining popularity in 2025 because they offer flexibility, transparency, and cost savings. Here’s why many organizations prefer them:
💰 Cost-Effective – No expensive licenses, perfect for startups and small businesses.
⚙️ Customizable – You can modify the source code to fit your exact requirements.
👥 Community Support – Get help, plugins, and updates from active global communities.
🔒 Transparency – Review the source code to ensure there are no hidden risks.
Top Open Source SSO Providers in 2025
1. Keycloak
Overview: Developed by Red Hat, Keycloak is one of the most popular open-source identity and access management (IAM) solutions. It supports SSO, social logins, and user federation — making it enterprise-ready.
Key Features:
Supports OAuth2, OpenID Connect, and SAML 2.0
Integrates with LDAP and Active Directory
Customizable themes and admin console
Backed by a strong community
Pros:
Scalable and ideal for large organizations
Supports multiple authentication protocols
Regular updates and strong documentation
Cons:
Complex setup for beginners
Deep customization needs Java or Quarkus expertise
2. Authentik
Overview: Authentik is a modern, open-source identity provider focused on simplicity and usability. It’s lightweight, easy to deploy, and perfect for small to mid-sized teams.
Key Features:
Supports OAuth2, OpenID Connect, and SAML
Built-in Multi-Factor Authentication (MFA)
Clean, user-friendly dashboard
Plugin support for custom integrations
Pros:
Simple setup — great for newcomers
Modern and intuitive UI
Strong security features out of the box
Cons:
Smaller community compared to Keycloak
Fewer advanced enterprise-level features
3. Zitadel
Overview: Zitadel is a next-generation open-source IAM platform built for scalability and enterprise-grade performance. It’s cloud-native, secure, and easy to integrate.
Key Features:
Supports OAuth2, OpenID Connect, and SAML
Cloud-native and horizontally scalable
Strong documentation and developer-friendly APIs
Supports B2B multi-tenancy
Pros:
Enterprise-ready and highly scalable
Smooth user experience
Frequent updates and active development
Cons:
Uses an event-sourcing architecture — may feel complex to some developers
Smaller ecosystem than Keycloak
B2B-focused model may feel overkill for small apps
Comparison Table
Feature | Keycloak | Authentik | Zitadel |
| OAuth2, OpenID Connect, SAML | OAuth2, OpenID Connect, SAML | OAuth2, OpenID Connect, SAML |
| Yes | Yes | Yes |
| Yes | Yes | Yes |
| Moderate | Easy | Easy |
| High | Moderate | High |
| High | Moderate | Moderate |
Conclusion: Which Open Source SSO Should You Choose in 2025?
Your choice depends on your team size and technical needs:
Keycloak – Best for large enterprises that need advanced control and scalability.
Authentik – Best for small to mid-sized businesses that want easy setup and strong security.
Zitadel – Best for modern, cloud-native teams focused on scalability and B2B identity management.
In 2025, open source SSO solutions are the smart way to manage user identity and access — giving you control, flexibility, and cost savings without vendor lock-in.
By choosing the right platform, you can enhance user experience, strengthen security, and simplify authentication across all your applications.