Keycloak
Battle-tested open-source identity and access management with SSO, OIDC, and SAML.
Last commit 2026-06-01
Keycloak is what you reach for when identity and access management needs to run on your infrastructure, handle thousands of internal users, and speak every enterprise federation protocol without a monthly bill. Originally developed by Red Hat and now a CNCF-incubating project, it has been running in production at large organizations since 2013 and carries a decade of security hardening that most newer alternatives can't match.
The feature surface is comprehensive. Keycloak acts as both an OIDC/OAuth 2.0 authorization server and a SAML 2.0 identity provider, brokers external IdPs including Google, GitHub, and corporate Active Directory instances, enforces MFA, supports fine-grained UMA 2.0 authorization, and manages user federation from LDAP and Active Directory with attribute synchronization. All of this is configurable through its admin console and exposed via a management REST API.
The honest cost of that power is operational weight. Keycloak is Java-based, which means a 512 MB container is not going to cut it — a modest cluster needs 1–2 GB per node minimum, and the JVM startup time makes horizontal scaling more deliberate than with Go-based alternatives. The admin console has improved considerably with the Quarkus rewrite, but navigating realms, clients, flows, and mappers still requires a meaningful learning investment. Teams with the Java expertise and the infrastructure to absorb it get a proven, extensible IAM that outperforms any SaaS offering on raw control and cost at scale.
Key features of Keycloak
- OpenID Connect and OAuth 2.0 server with full spec compliance
- SAML 2.0 identity provider and service provider
- User federation with LDAP and Active Directory
- Fine-grained authorization with UMA 2.0 support
- Themes and custom login pages via FreeMarker templates
- High-availability clustering via Infinispan and JDBC session storage
Pros
- Apache-2.0 licensed — completely free with no seat or MAU limits
- CNCF-incubating project with Red Hat backing and a decade of production hardening
- Supports every major enterprise federation protocol (LDAP, AD, SAML, OIDC)
Cons
- Java-based stack is resource-heavy and slow to cold-start compared to modern alternatives
- Admin UI and realm configuration have a steep learning curve
- Extension development requires Java and understanding of Keycloak's SPI architecture
Keycloak pricing
Free / self-host · open-source · Apache-2.0
Enterprise teams and regulated industries that need full IAM control on their own infrastructure and don't want vendor bills.
Keycloak is an alternative to
Head-to-head comparisons
Frequently asked questions
Is Keycloak open source?
Yes. Keycloak is open source (Apache-2.0), so you can read the code, self-host it, and avoid vendor lock-in.
How much does Keycloak cost?
Keycloak starts at Free / self-host on a open-source model. Self-hosting can reduce that to infrastructure cost only.
Can I self-host Keycloak?
Yes — Keycloak supports self-hosting, giving you full data ownership.