Gluu Flex vs Keycloak
A side-by-side comparison of two self-hosted identity & sso options — licensing, setup difficulty, resource needs, and what each one replaces.
Keycloak
Open-source identity and access management for modern apps
| Feature | Gluu Flex | Keycloak |
|---|---|---|
| Deploy effort | Under-an-hour setup | Under-an-hour setup |
| Health score | 69 · Good | 99 · Excellent |
| Category | Identity & SSO | Identity & SSO |
| License | Apache-2.0 | Apache-2.0 |
| Language | TypeScript | Java |
| Setup difficulty | Hard | Hard |
| Min. RAM | 4,096 MB | 1,024 MB |
| Deployment | docker, kubernetes, helm | docker, kubernetes, bare-metal |
| GitHub stars | ★ 31 | ★ 36,967 |
| First released | 2009 | 2014 |
| Replaces | Okta, Ping Identity | Okta, Auth0, Microsoft Entra ID |
What are Gluu Flex and Keycloak?
Gluu Flex
Gluu provides a self-hostable identity platform for single sign-on, multi-factor authentication, and access management built on open standards. It supports OAuth, OIDC, SAML, and FIDO2.
- Single sign-on
- OAuth, OIDC and SAML
- FIDO2 strong authentication
- Kubernetes deployment
Keycloak
Keycloak is an enterprise-grade identity and access management solution backed by Red Hat. It provides single sign-on, identity brokering, social login and fine-grained authorization for applications and services.
- SSO with OpenID Connect and SAML 2.0
- Identity brokering and social login
- User federation with LDAP and Active Directory
- Fine-grained authorization services
Gluu Flex vs Keycloak: key differences
Gluu Flex is written in TypeScript, while Keycloak is built with Java. Keycloak is the lighter option, starting around 1,024 MB of RAM against 4,096 MB for Gluu Flex. Gluu Flex is the more established project (first released 2009), while Keycloak arrived in 2014. Keycloak has the considerably larger community, at 36,967 GitHub stars versus 31.
Why pick each one
Choose Gluu Flex if…
- Released under the Apache-2.0 license
- First-class Docker support for quick deployment
- Kubernetes-ready with Helm charts available
- Written in TypeScript
Choose Keycloak if…
- Mature and battle-tested
- Strong enterprise feature set
Watch out for
- Steep learning curve
- Resource intensive
Frequently asked questions
Is Gluu Flex or Keycloak better?
Neither is universally better. Keycloak has the larger community; both share a hard setup difficulty, so the decision comes down to features and licensing.
Are Gluu Flex and Keycloak free and open-source?
Yes. Gluu Flex is licensed under Apache-2.0 and Keycloak under Apache-2.0. Both can be self-hosted at no software cost.
Can I run Gluu Flex and Keycloak with Docker?
Gluu Flex: yes. Keycloak: yes.
Which is lighter on resources, Gluu Flex or Keycloak?
Keycloak has the smaller minimum footprint at 1,024 MB of RAM, compared to about 4,096 MB for Gluu Flex. Real-world usage depends on library size, user count, and enabled features.