Top 10 Open Source IAM Solutions in 2026: Complete Comparison Guide

Choosing an Identity and Access Management (IAM) platform is one of the most consequential infrastructure decisions a development team can make. The right choice secures your users and simplifies your architecture; the wrong one creates years of technical debt. In 2026, the open source IAM landscape is more mature and more competitive than ever, with options ranging from full-featured enterprise platforms to lightweight, developer-first libraries.

This guide compares the top 10 open source IAM solutions across features, community health, deployment complexity, and ideal use cases. Whether you are building a SaaS product, securing internal tools, or replacing a legacy identity provider, this comparison will help you make an informed decision.

If you are new to open source IAM, our Getting Started with Keycloak guide is a practical starting point.

Quick Comparison Table

1. Keycloak

Overview: Keycloak is the most widely adopted open source IAM platform, originally developed by Red Hat and now a CNCF incubating project. It provides a complete identity provider with built-in support for OpenID Connect, SAML 2.0, OAuth 2.0, and LDAP/Active Directory federation. The migration to a Quarkus runtime in recent versions has significantly improved startup time and memory efficiency.

Key Features:

• Full OIDC and SAML 2.0 identity brokering and service provider support
• Built-in admin console and account management portal
• User federation with LDAP, Active Directory, and custom providers via SPI
• Fine-grained authorization services with UMA 2.0 support
• Kubernetes-native deployment with official Operator

Best For: Organizations that need a full-featured, standards-compliant identity provider with a proven track record in production. Keycloak is the default choice for teams that want everything in one package.

Limitations: Resource-heavy compared to Go-based alternatives. The admin console, while comprehensive, has a steep learning curve. Customizing login themes requires working with FreeMarker templates or the newer Account Console v3.

Community: ~25,000 GitHub stars. One of the largest IAM communities with active mailing lists, a Discourse forum, and extensive third-party documentation. Backed by Red Hat and the CNCF.

For a deeper dive, see our Keycloak Complete Guide and our comparison of ForgeRock, Ping, Auth0, and Keycloak.

2. Ory (Hydra + Kratos)

Overview: Ory takes a modular, API-first approach to identity. Rather than a monolithic IdP, Ory provides separate components: Ory Hydra is an OpenID Certified OAuth 2.1 and OIDC server, and Ory Kratos is a headless identity management system handling registration, login, MFA, and account recovery. This separation of concerns is ideal for teams building microservices architectures. Ory is trusted by organizations like OpenAI for scale and security.

Key Features:

• Hydra: OpenID Certified OAuth 2.1 provider with consent flow delegation
• Kratos: Headless identity management with passkeys, social sign-in, TOTP, and WebAuthn
• Zero vendor lock-in with bring-your-own-UI philosophy
• Ory Oathkeeper for API gateway-level access control
• Available as self-hosted or managed (Ory Network)

Best For: Engineering teams building custom authentication experiences in microservices environments. Ideal when you need an OAuth/OIDC server without a bundled UI.

Limitations: No built-in admin UI – everything is API and CLI driven. Requires assembling multiple components. The learning curve is steep for teams unfamiliar with OAuth 2.0 flows. Documentation, while thorough, assumes significant prior knowledge.

Community: Hydra has ~17,000 GitHub stars; Kratos has ~13,000. Active Discord community and GitHub Discussions. Ory has strong enterprise adoption among engineering-heavy organizations.

3. Zitadel

Overview: Zitadel is a cloud-native IAM platform built from the ground up for multi-tenancy. Written in Go, it combines identity management, authentication, and authorization into a single binary. Zitadel uses an event-sourced architecture that provides a full audit trail of every identity change, making it particularly appealing for compliance-sensitive environments.

Key Features:

• Built-in multi-tenancy with organizations, projects, and role-based grants
• Event-sourced architecture providing complete audit trail
• Passwordless authentication with FIDO2/WebAuthn support
• Actions system for custom logic (similar to Auth0 Actions)
• Single binary deployment with embedded CockroachDB or PostgreSQL

Best For: SaaS companies that need to manage identity across multiple tenants with strong audit requirements. Zitadel’s B2B features like delegated user management make it stand out.

Limitations: Younger project with a smaller ecosystem of integrations compared to Keycloak. SAML support is more recent and less battle-tested. Limited selection of social login providers compared to mature platforms.

Community: ~13,000 GitHub stars. Active GitHub Discussions and Discord. The project has seen rapid growth since its open source launch, with consistent release cadence.

4. Gluu Server (Janssen Project)

Overview: The Gluu Server, now built on the Janssen Project (a Linux Foundation project), is one of the oldest open source IAM platforms. It focuses heavily on standards compliance and enterprise-grade identity federation. The Janssen Project includes an OAuth/OIDC authorization server, the Agama low-code identity orchestration engine, and the Cedarling policy decision point. Gluu Flex is the commercial distribution.

Key Features:

• OpenID Certified authorization server with full FIDO2 support
• Agama: low-code identity orchestration for complex authentication flows
• Cedarling: Cedar-based policy decision engine for fine-grained authorization
• SCIM 2.0 for user provisioning and lifecycle management
• Recognized as a Digital Public Good by the DPGA

Best For: Regulated enterprises (government, healthcare, finance) that need certified standards compliance and are willing to invest in deployment complexity.

Limitations: Complex installation and configuration. Smaller community compared to Keycloak and Ory. Documentation can be fragmented across Gluu and Janssen Project resources. The transition from Gluu 4.x to Janssen-based Gluu 5/Flex has created some confusion.

Community: ~600 GitHub stars for the Janssen monorepo. While the star count is lower, Gluu has a dedicated enterprise user base and backing from the Linux Foundation. Active community support through the Gluu Forum.

5. WSO2 Identity Server

Overview: WSO2 Identity Server is a Java-based IAM platform that integrates deeply with the broader WSO2 middleware stack (API Manager, Enterprise Integrator). It provides comprehensive identity federation, adaptive authentication, and consent management. WSO2 offers both an open source community edition and a commercial subscription.

Key Features:

• Adaptive authentication with risk-based conditional flows
• WS-Federation support alongside OIDC, SAML, and SCIM
• Consent management for GDPR and privacy compliance
• Deep integration with WSO2 API Manager for API security
• Template-based authentication flow customization

Best For: Organizations already in the WSO2 ecosystem or those needing tight coupling between API management and identity. Strong choice for enterprises that need WS-Federation alongside modern protocols.

Limitations: Requires significant Java and WSO2 ecosystem knowledge. Heavy resource footprint. The open source community edition lags behind the commercial version in features and updates. UI modernization has been slower than competitors.

Community: ~950 GitHub stars on the product repository. WSO2 has a dedicated enterprise community with active Stack Overflow presence and annual conferences (WSO2Con). Commercial support is available through WSO2 subscriptions.

6. Authentik

Overview: Authentik is a Python-based identity provider that has quickly become the go-to choice for self-hosted environments and small-to-medium businesses. It combines an intuitive web UI with robust protocol support, including OIDC, SAML, LDAP (as both consumer and provider), and SCIM. Authentik stands out for its “flow” system that lets administrators build custom authentication workflows visually.

Key Features:

• Visual flow designer for custom authentication and enrollment workflows
• Acts as both LDAP consumer and LDAP provider (proxying modern auth to legacy apps)
• Built-in application proxy for securing applications without native OIDC/SAML support
• SCIM provisioning for downstream identity synchronization
• Outpost architecture for distributed deployment

Best For: Homelab enthusiasts, small-to-medium businesses, and DevOps teams looking for a self-hosted IdP with a polished UI and minimal configuration effort.

Limitations: Python-based, which may raise performance concerns at very high scale compared to Go or Java alternatives. Enterprise features like high availability require the Enterprise license. Smaller ecosystem of extensions compared to Keycloak.

Community: ~15,000 GitHub stars. Very active Discord community and GitHub Discussions. The project has experienced explosive growth, driven largely by the self-hosting community.

7. Authelia

Overview: Authelia is a lightweight authentication and authorization server designed specifically to work with reverse proxies like Nginx, Traefik, HAProxy, and Caddy. Written in Go, it provides SSO and two-factor authentication for applications sitting behind a reverse proxy. It is now OpenID Certified.

Key Features:

• Seamless integration with major reverse proxies (Nginx, Traefik, HAProxy, Caddy, Envoy)
• OpenID Connect provider (OpenID Certified)
• Multiple second-factor methods: TOTP, WebAuthn/FIDO2, Duo Push
• Lightweight single binary with minimal resource requirements
• Configurable access control rules based on domain, resource, and user/group

Best For: Self-hosting enthusiasts and DevOps teams who want to add SSO and MFA to applications behind a reverse proxy without modifying the applications themselves.

Limitations: Not a full-featured IdP – lacks SAML support, user provisioning (SCIM), and identity brokering. Focused narrowly on reverse proxy authentication. No built-in admin UI for user management (users are managed via LDAP/file backends). Limited to forward-auth and OpenID Connect patterns.

Community: ~22,000 GitHub stars. One of the most popular projects in the self-hosting space. Active GitHub Discussions, Matrix chat, and Discord. Strong documentation focused on integration recipes for various reverse proxies.

8. FusionAuth (Community Edition)

Overview: FusionAuth is a developer-focused authentication platform that offers a Community Edition with free-forever licensing. While not fully open source (the core is source-available under a custom license), the Community Edition provides a full-featured auth server with no user limits. FusionAuth is written in Java and known for its polished admin console and developer experience.

Key Features:

• Polished, modern admin console with extensive self-service capabilities
• Advanced login theming with full HTML/CSS/JS control
• Tenant-aware architecture for multi-application and multi-tenant deployments
• Breached password detection and advanced threat detection
• Comprehensive client libraries across all major languages and frameworks

Best For: Startups and development teams that want a ready-to-use auth server with a polished developer experience and UI. Teams that need advanced features like breached password detection without an enterprise contract.

Limitations: Source-available rather than truly open source – cannot fork and modify freely. Some features (SCIM provisioning, advanced MFA, connectors) require a paid license. Community support is limited compared to fully open source projects.

Community: FusionAuth uses a source-available model, so GitHub engagement metrics are not directly comparable. Active community forum and Slack channel. The company is venture-backed with a growing customer base.

9. Casdoor

Overview: Casdoor is a UI-first IAM and SSO platform built with Go (backend) and React (frontend). It emphasizes ease of use, offering a clean web UI for managing users, organizations, applications, and providers. Casdoor supports a wide range of protocols and over 40 third-party identity providers out of the box.

Key Features:

• Clean, modern web UI for identity administration with multi-language support
• 40+ social login providers supported out of the box
• OAuth 2.0, OIDC, SAML, CAS, LDAP, SCIM, WebAuthn, RADIUS, and Kerberos support
• Face ID and multi-factor authentication
• Integration with Casbin for fine-grained authorization (RBAC, ABAC)

Best For: Teams that want a visually intuitive SSO portal with broad protocol support and don’t want to spend time customizing login UIs. Good fit for organizations that need to support many social login providers.

Limitations: Smaller international community – much of the documentation and discussion is in Chinese. Less battle-tested in large enterprise environments compared to Keycloak or Gluu. Integration documentation for specific frameworks can be sparse.

Community: ~11,000 GitHub stars. Active development with frequent releases. The community is growing, particularly in the Chinese-speaking developer ecosystem. Integrates with the broader Casbin authorization ecosystem.

10. SuperTokens

Overview: SuperTokens is an open source authentication solution designed for application developers who want to add auth to their apps without deploying a full IdP. It provides pre-built UI components and backend SDKs for common auth flows (email/password, social login, passwordless, session management). The SuperTokens core is written in Java, with first-class SDKs for Node.js, Python, and Go.

Key Features:

• Pre-built, customizable login UI components for React, Vue, and vanilla JS
• Session management with automatic token rotation and anti-CSRF protection
• Passwordless authentication via magic links and OTPs
• Multi-tenancy support with per-tenant login methods
• Self-hosted or managed cloud option with generous free tier

Best For: Application developers building products who want to add authentication quickly without deploying and managing a separate IdP. Ideal for teams using Node.js, Python, or Go backends.

Limitations: Narrower scope than full IAM platforms – focused on application-level auth rather than enterprise identity federation. SAML and LDAP support are limited. Not suitable as a centralized IdP for an organization with many applications. Enterprise features like account linking across tenants require the paid tier.

Community: ~14,000 GitHub stars. Active Discord community with responsive maintainers. Strong documentation with framework-specific guides. Growing adoption among startups and indie developers.

How to Choose the Right Open Source IAM Solution

Selecting an IAM platform depends on your specific requirements, team capabilities, and deployment environment. Here is a framework for making the decision.

By Use Case

Enterprise IdP replacing commercial software: Start with Keycloak. It offers the closest feature parity to commercial solutions like ForgeRock or Ping Identity. See our ForgeRock vs Keycloak comparison for a detailed analysis of trade-offs.

Microservices with custom auth UX: Choose Ory (Hydra + Kratos). The headless, API-first architecture gives you complete control over the user experience while providing certified OAuth 2.1 and OIDC support.

Multi-tenant SaaS product: Consider Zitadel for its native multi-tenancy and event-sourced audit trail, or FusionAuth if you prefer a more polished out-of-the-box UI.

Self-hosted homelab or small team: Authelia if you primarily need reverse proxy authentication and SSO, or Authentik if you need a more complete IdP with SAML and LDAP support.

Regulated industry with compliance requirements: Gluu (Janssen) offers the strongest standards compliance and is backed by the Linux Foundation. WSO2 Identity Server is another option if you need WS-Federation or deep API management integration.

Quick auth for a new application: SuperTokens or Casdoor provide the fastest path to production auth with pre-built components and minimal infrastructure.

By Team Expertise

Key Decision Factors

1. Protocol requirements: If you need SAML, your options narrow to Keycloak, Ory Hydra (via proxy), Zitadel, Gluu, WSO2, Authentik, Casdoor, and FusionAuth. Authelia and SuperTokens have limited or no SAML support.

2. Deployment model: All solutions support self-hosting. Several also offer managed cloud options (Ory Network, Zitadel Cloud, SuperTokens Managed, FusionAuth Cloud). Evaluate whether you want to run your own identity infrastructure or offload that operational burden.

3. Community and longevity: Keycloak (CNCF), Gluu/Janssen (Linux Foundation), and Ory have the strongest organizational backing. Consider the bus factor and funding model of any project you depend on for authentication.

4. Scale requirements: For internet-scale deployments, Go-based solutions (Ory, Zitadel, Authelia) generally offer better performance per resource unit. Java-based solutions (Keycloak, WSO2, FusionAuth) offer mature clustering but require more infrastructure.

5. Customization depth: Ory and SuperTokens provide the most flexibility for custom UIs. Keycloak and Authentik offer the most complete built-in UIs. Choose based on whether you want to build or configure.

No single solution is universally “best.” The right IAM platform is the one that matches your team’s skills, your application’s requirements, and your organization’s operational capacity. Start with a proof of concept on your top two candidates before committing.