Keycloak vs Zitadel

The honest comparison

Keycloak and Zitadel score 4.2 and 4.0, and both answer the same question: how do you run a capable identity provider without per-user licensing.

Keycloak is the incumbent. A CNCF project sponsored by Red Hat, free under Apache 2.0, supporting OIDC and SAML with an extension model that lets you customize authentication flows, storage, and protocol mappers almost without limit. Commercial support exists through the Red Hat build and third parties. The trade is weight: a large configuration surface, meaningful upgrade planning, and an architecture that predates the API-first expectation.

Zitadel is the modern take. Open core, API-first, multi-tenant by design, with passkeys and an event-sourced audit trail as defaults rather than add-ons, plus a managed cloud with published pricing if you would rather not operate it. It is younger, with a smaller ecosystem and fewer people who have hit your problem before.

When Keycloak wins

• You need the most mature, widely deployed open-source identity provider available
• Deep customization through the extension model, including custom authentication flows and user storage
• Commercial support with SLAs matters, available through the Red Hat build
• Complex SAML federation requirements alongside modern protocols
• A large community and a decade of documented answers to operational problems

When Zitadel wins

• Multi-tenancy is a first-class requirement rather than something you model yourself
• API-first management fits how your team works, with configuration as code rather than console clicks
• Passkeys and a strong audit trail as defaults rather than configuration projects
• You want a managed cloud option with transparent pricing as an escape from self-hosting
• Smaller operational footprint matters more than ecosystem depth

Pricing

Keycloak is free under Apache 2.0 with no licence cost at any scale; you pay for infrastructure and for commercial support if you want SLAs. Zitadel is open source and free to self-host, with a managed cloud on a transparent published model including a free tier, and paid enterprise self-host support.

The real number in both cases is operations. An identity provider outage is a full outage, so budget an owner, an upgrade cadence, and a tested restore path. Model it honestly against managed alternatives with the TCO calculator.

Verdict

For maximum maturity, ecosystem, and the option of vendor-supported distribution, Keycloak. For a modern, multi-tenant, API-first identity provider with passkeys by default and a managed cloud available, Zitadel. See FusionAuth vs Keycloak, SuperTokens vs FusionAuth, and the open source vendor category.