The State of Open-Source Identity in 2025: Authentik vs Authelia vs Keycloak vs Zitadel
- Philip Moses
- 4 days ago
- 4 min read
Updated: 21 hours ago
In 2025, managing digital identity is more than just single sign-on (SSO) or password management. Businesses today run cloud-native apps, microservices, and SaaS platforms where users expect secure, seamless, and scalable access. This makes choosing the right open-source Identity Provider (IdP) critical for developers, architects, and IT leaders.
In this blog, we compare four of the most popular open-source IAM (Identity and Access Management) platforms—Zitadel, Keycloak, Authentik, and Authelia. You’ll see how they differ in architecture, features, scalability, and use cases, helping you decide the best fit for your project in 2025.
Zitadel: Built for the Cloud and the Future
Zitadel is a Go-based, API-first platform with an event-sourced architecture. Every login, role change, or policy update is stored as an event, making it highly secure and fully auditable. It’s designed for cloud-native and SaaS applications that require multi-tenancy, high availability, and developer-friendly APIs.
Key Highlights in 2025
Event-sourced design with PostgreSQL as the main database.
API v2 with gRPC for faster, more consistent integrations.
AI-powered threat detection that learns from attacks across all deployments.
Strong focus on scalability and zero-downtime updates.
Zitadel stands out for modern SaaS and multi-tenant projects where developer experience and long-term scalability are top priorities.
Keycloak: The Enterprise Standard
Keycloak has been the go-to enterprise IAM solution for years. Backed by Red Hat and part of the CNCF incubation program, it is widely adopted in large organizations. Its Java-based architecture is battle-tested, making it reliable for complex enterprise integrations.
Key Highlights in 2025
Argon2 as the default password hashing algorithm.
Dropped old Java adapters for a leaner, modern ecosystem.
Persistent user sessions for high-availability deployments.
Strong support for OIDC, SAML, and UMA 2.0 authorization.
Keycloak is best for large-scale enterprise systems that require stability, deep features, and legacy integration support.
Authentik: Simple, Modern, and Flexible
Authentik is known for its clean UI and “flow” system, which lets you build custom authentication and authorization journeys. Written in Python, it balances simplicity with flexibility, making it popular among SMBs and home labs.
Key Highlights in 2025
Powerful flow-based authentication engine.
Passkeys and passwordless authentication support.
GeoIP checks to block suspicious login attempts.
Moved Remote Access Control (RAC) from paid to free, boosting community adoption.
Authentik is ideal for small-to-medium businesses or teams that value ease of use, modern UI, and flexibility without enterprise-level complexity.
Authelia: The Lightweight Security Gatekeeper
Unlike the others, Authelia is not a full IdP but a reverse proxy companion that acts as a security gatekeeper. It works as “forward auth,” sitting in front of apps to verify authentication before granting access.
Key Highlights in 2025
Now OIDC Certified™, ensuring compliance with open standards.
Passkeys and passwordless authentication support.
Uses a new minimal container image with reduced attack surface.
Lightweight and secure, perfect for self-hosted environments.
Authelia is best for small, self-hosted projects where you need a minimal, no-frills, and secure gatekeeper.
Comparison Table: Open-Source Identity in 2025
Feature | Zitadel | Keycloak | Authentik | Authelia |
| Cloud-native, SaaS, Multi-tenant | Enterprises, Legacy Systems | SMBs, Modern Teams | Self-hosted, Lightweight Gatekeeper |
| Event-sourced, API-first (Go) | Java-based, CNCF-backed | Python-based Workflow Engine | Go-based, Reverse Proxy Companion |
| AI threat detection, API v2 | Argon2, Persistent Sessions | Passkeys, GeoIP, RAC Free | Passkeys, OIDC Certified, Minimalist |
| Cloud + Self-hosted (K8s) | Self-hosted + 3rd-party Managed | Self-hosted (K8s/Docker) | Self-hosted (K8s/Docker) |
| AGPL3 | Apache 2.0 | Apache 2.0 / BSD-3 | Apache 2.0 |
| Scalable, API-first, Modern | Mature, Feature-rich, Trusted | Easy UI, Flexible workflows | Lightweight, Secure, Minimal |
| Newer, AGPL may limit adoption | Heavy, Complex UI, Java-based | Needs PostgreSQL/Redis | Limited scope, Needs Reverse Proxy |
Final Verdict: Which One Should You Choose?
✅ Choose Authelia if you want a simple, secure gatekeeper for self-hosted apps.
✅ Choose Authentik if you need a flexible, modern solution for SMBs or smaller teams.
✅ Choose Keycloak if you’re running a large enterprise system with legacy needs and require a trusted, battle-tested platform.
✅ Choose Zitadel if you’re building a modern SaaS or cloud-native application and want scalability, developer-first APIs, and future-ready AI-driven security.
In short, all four are excellent open-source identity solutions in 2025—but the right choice depends on your scale, use case, and long-term vision.
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