Keycloak vs Ory Hydra
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
VS
Ory Hydra
Certified OAuth 2.0 and OpenID Connect server
| Feature | Keycloak | Ory Hydra |
|---|---|---|
| Deploy effort | Under-an-hour setup | Under-an-hour setup |
| Health score | 99 · Excellent | 90 · Excellent |
| Category | Identity & SSO | Identity & SSO |
| License | Apache-2.0 | Apache-2.0 |
| Language | Java | Go |
| Setup difficulty | Hard | Hard |
| Min. RAM | 1,024 MB | 256 MB |
| Deployment | docker, kubernetes, bare-metal | docker, kubernetes, binary |
| GitHub stars | ★ 36,967 | ★ 17,563 |
| First released | 2014 | 2015 |
| Replaces | Okta, Auth0, Microsoft Entra ID | Okta, Auth0 |
What are Keycloak and Ory Hydra?
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
Ory Hydra
Ory Hydra is an OpenID Certified OAuth 2.0 and OpenID Connect provider. It is built to integrate with any existing identity system and issues tokens without managing user accounts itself.
- OpenID Certified implementation
- Low memory footprint
- Bring your own login and consent UI
- Scales horizontally
Keycloak vs Ory Hydra: key differences
Keycloak is written in Java, while Ory Hydra is built with Go. Ory Hydra is the lighter option, starting around 256 MB of RAM against 1,024 MB for Keycloak. Keycloak has the considerably larger community, at 36,967 GitHub stars versus 17,563.
Why pick each one
Choose Keycloak if…
- Mature and battle-tested
- Strong enterprise feature set
Watch out for
- Steep learning curve
- Resource intensive
Choose Ory Hydra if…
- Security focused and certified
- Integrates with any user store
Watch out for
- Only handles OAuth, not user management
Frequently asked questions
Is Keycloak or Ory Hydra 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 Keycloak and Ory Hydra free and open-source?
Yes. Keycloak is licensed under Apache-2.0 and Ory Hydra under Apache-2.0. Both can be self-hosted at no software cost.
Can I run Keycloak and Ory Hydra with Docker?
Keycloak: yes. Ory Hydra: yes.
Which is lighter on resources, Keycloak or Ory Hydra?
Ory Hydra has the smaller minimum footprint at 256 MB of RAM, compared to about 1,024 MB for Keycloak. Real-world usage depends on library size, user count, and enabled features.