Gluu Flex vs ZITADEL
A side-by-side comparison of two self-hosted identity & sso options — licensing, setup difficulty, resource needs, and what each one replaces.
ZITADEL
Cloud-native identity infrastructure with multi-tenancy built
| Feature | Gluu Flex | ZITADEL |
|---|---|---|
| Deploy effort | Under-an-hour setup | Under-an-hour setup |
| Health score | 69 · Good | 95 · Excellent |
| Category | Identity & SSO | Identity & SSO |
| License | Apache-2.0 | Apache-2.0 |
| Language | TypeScript | Go |
| Setup difficulty | Hard | Medium |
| Min. RAM | 4,096 MB | 512 MB |
| Deployment | docker, kubernetes, helm | docker, kubernetes, binary |
| GitHub stars | ★ 31 | ★ 15,083 |
| First released | 2009 | 2020 |
| Replaces | Okta, Ping Identity | Auth0, Okta, Firebase Auth |
What are Gluu Flex and ZITADEL?
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
ZITADEL
ZITADEL is an open-source identity and access management platform built for multi-tenant applications. It offers OpenID Connect, OAuth2, SAML, passwordless login and a powerful management API.
- Multi-tenancy as a first-class concept
- Passwordless and FIDO2 authentication
- Event-sourced audit trail
- Comprehensive gRPC and REST APIs
Gluu Flex vs ZITADEL: key differences
Gluu Flex is written in TypeScript, while ZITADEL is built with Go. ZITADEL is the lighter option, starting around 512 MB of RAM against 4,096 MB for Gluu Flex. Gluu Flex is the more established project (first released 2009), while ZITADEL arrived in 2020. ZITADEL has the considerably larger community, at 15,083 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 ZITADEL if…
- Strong multi-tenant model
- Modern Go codebase
Watch out for
- Smaller community than Keycloak
Frequently asked questions
Is Gluu Flex or ZITADEL better?
ZITADEL is the stronger all-round pick: it has both the larger community and the simpler medium setup. Consider Gluu Flex if its specific feature set fits your needs better.
Are Gluu Flex and ZITADEL free and open-source?
Yes. Gluu Flex is licensed under Apache-2.0 and ZITADEL under Apache-2.0. Both can be self-hosted at no software cost.
Can I run Gluu Flex and ZITADEL with Docker?
Gluu Flex: yes. ZITADEL: yes.
Which is lighter on resources, Gluu Flex or ZITADEL?
ZITADEL has the smaller minimum footprint at 512 MB of RAM, compared to about 4,096 MB for Gluu Flex. Real-world usage depends on library size, user count, and enabled features.