Open-Source IAM Comparison: Keycloak vs Authentik vs Zitadel vs Kanidm

You've decided on open-source IAM - now which platform? This page helps you choose between the main open-source options. If you're still evaluating open-source against SaaS products like Okta and Auth0, see our SaaS vs open-source cost comparison.

Quick comparison

Authentik

Strengths: Authentik has a modern, well-designed interface and a visual flow-based policy engine that makes authentication logic accessible without writing code. The Python extensibility model lets you add custom logic through expressions and stages without compiling Java SPIs. It added SCIM provisioning early and has a clear development trajectory. For teams evaluating Keycloak's UI complexity as a barrier, Authentik is the most credible alternative.

Limitations: Authentik's ecosystem is smaller than Keycloak's. Production references at large scale (100k+ users, high availability, complex enterprise federation) are fewer and harder to find. There is no commercially backed support offering - you rely on the community or paid third-party consultants. If your integrations depend on specific SAML edge cases or Kerberos, Keycloak has broader protocol coverage. The Python codebase also adds a runtime dependency that some security teams scrutinise.

Zitadel

Strengths: Zitadel is built by a Swiss company based in St. Gallen. It is written in Go, which gives it a small binary footprint and cloud-native runtime characteristics. The built-in gRPC API makes it well-suited to infrastructure-as-code workflows: you manage tenants, applications, and policies via API rather than clicking through a UI. Zitadel's Organizations model provides first-class multi-tenancy and is actively developed.

Limitations: Zitadel's SAML support is less mature than Keycloak's - enterprises with large SAML app estates should test compatibility carefully before committing. The plugin and extension ecosystem is smaller, and Zitadel GmbH is the primary commercial backer, so ecosystem breadth depends on their roadmap. Kubernetes deployment is handled via Helm chart with the gRPC management API, but there is no Kubernetes operator equivalent to the Keycloak Operator.

Kanidm

Strengths: Kanidm is written in Rust and designed from scratch with a security-first architecture. It avoids legacy protocol baggage and makes deliberate choices to reduce attack surface - for example, defaulting to modern cryptography and refusing to implement weaker compatibility modes. For teams building greenfield infrastructure who want a modern, auditable IAM stack, Kanidm is worth following.

Limitations: Kanidm is early stage. Protocol coverage is limited - SAML is not supported, which rules it out for most enterprise environments with existing SAML app integrations. The community is small and the project has not yet reached the operational maturity needed for most production enterprise deployments. Kanidm is suitable for evaluation and development workloads, but not as a primary IAM platform for regulated environments today.

WSO2 Identity Server

WSO2 Identity Server is an enterprise-grade Java IAM platform with a long history. It is open source (Apache 2.0) but complex to operate and customise - it follows the same pattern as Keycloak but with heavier tooling and a steeper learning curve. Without WSO2's commercial support, operational complexity is high. It is less commonly chosen for new deployments in Europe.

VSHN + Inventage: operations and application expertise

VSHN operates Keycloak infrastructure on Swiss cloud, including monitoring, backups, upgrades, and high-availability configuration. Inventage provides application-layer Keycloak expertise: custom authentication flows, SSO integrations, theme development with Keycloakify, and identity architecture consulting.

This combination covers the full stack: you are not choosing between infrastructure operations and application expertise, you get both. No other provider in Switzerland offers this partnership for managed Keycloak.

For Authentik, Zitadel, or Kanidm, you would need to assemble your own operations and development support. VSHN has expertise in all four platforms for assessment work, but managed operations are available for Keycloak only.

When to choose each option

Choose Keycloak when: - You need mature SAML, OIDC, LDAP, and Kerberos support in a single platform - You need proven large-scale production deployments and a large community for reference - Your team or partner (Inventage) has Java skills for custom SPI development - You want a CNCF-graduated project with mature project governance independent of any single vendor, Red Hat commercial backing, and long-term support - You want managed operations from VSHN with a fixed monthly price

Choose Authentik when: - Your team prefers Python over Java for extension development - You want a modern visual flow designer and a cleaner admin interface - Your SAML requirements are standard and well-covered - You are comfortable managing your own operations without commercial support

Choose Zitadel when: - You prefer a Swiss-built product with a Swiss vendor (note: VSHN Managed Keycloak also provides Swiss data residency and Swiss operations) - You have infrastructure-as-code workflows and want full gRPC API management - Your app estate is primarily OIDC-based - You want a Go-native, cloud-native binary with low resource overhead

Choose Kanidm when: - You are building greenfield infrastructure and can accept early-stage software - You want to evaluate a security-first Rust-based IAM platform - You do not require SAML support

Evaluate Keycloak for your environment

VSHN and Inventage offer a free 15-minute initial call to assess your current IAM setup, review your protocol and integration requirements, and estimate migration effort from your existing platform. Book a consultation.