head to head · open source
Keycloak vs hydra
Keycloak has 36,876 GitHub stars, 8,945 forks, 3,292 open issues and last shipped today. hydra has 17,553 stars, 1,609 forks, 98 open issues and last shipped 2 months ago. Keycloak leads on adoption by 110% (36,876 vs 17,553 stars). Keycloak is written in Java under Apache-2.0; hydra is written in Go under Apache-2.0. Keycloak has attracted 24% as many forks as stars, hydra 9%. Keycloak was the more recently maintained of the two, and both are self-hostable with no licence fee.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
← all 20902 open source comparisons
Side by side
| Keycloak | hydra | |
|---|---|---|
| GitHub stars | ★ 37K | ★ 18K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Java | Go |
| Last push | 2026-09-20 | 2026-07-29 |
| Forks | ⑂ 8.9K | ⑂ 1.6K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Keycloak if
- You weight community size — 37K stars and counting
- You want the Apache-2.0 license terms
- Your stack matches Java
- You value the larger contributor base for long-term maintenance
pick hydra if
- You want the hydra feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Go
- You evaluated both and hydra fits your workflow better
About Keycloak
Keycloak is an open source identity and access management server, written in Java and licensed under Apache 2.0, that adds authentication and access control to applications and services, and it is intended for teams and organisations that want to own their user store rather than rent one.
read the full Keycloak overview →
About hydra
Ory Hydra is an OpenID Certified OpenID Connect and OAuth 2.1 provider written in Go and licensed under Apache 2.0, built for teams that need standards compliant token issuance, client management, and consent flows while user accounts stay in their own existing identity system.
read the full hydra overview →
More in Security & Privacy
Related comparisons
More Identity & Access Management (IAM) projects
Compare either of these against the rest of the Identity & Access Management (IAM) field.
Frequently asked questions
Is Keycloak or hydra more popular?
Keycloak has 36,876 GitHub stars and hydra has 17,553. Keycloak has the larger community by that measure.
Are Keycloak and hydra free?
Both are open source. Keycloak is licensed under Apache-2.0 and hydra under Apache-2.0. Neither carries a licence fee.
What is the difference between Keycloak and hydra?
Keycloak is written in Java and hydra in Go. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Keycloak or hydra?
Choose Keycloak if you want the larger community (36,876 stars) or its Apache-2.0 licence terms. Choose hydra if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.