Keycloak vs Prometheus
The ultimate side-by-side head-to-head analysis for 2026.
Short answer
- Price: both start at Free.
- How to start: both are free.
These lines are generated from the pricing we track, not from a paid placement. We do not publish a quality score, because we do not have one we can stand behind. They cannot tell you which tool fits your workflow — the sections below are there for that. How we score tools.
Keycloak
Prometheus
Category
Developer Tools
Developer Tools
Base Price
Free
Free
Public API
Yes
Yes
Mobile app
No
No
Open source / self-hostable
Yes
Yes
SSO (SAML)
Yes
No
Choose Keycloak if:
Organisations that need enterprise identity without a per-user bill.
Choose Prometheus if:
Teams running services that need metrics and alerting they control.
Keycloak: pros & cons
- Full identity server at no licence cost
- Standards support including SAML and OIDC
- Complete control over user data
- Operating it is a real responsibility
- Administration console is dense
- Upgrades need care
Prometheus: pros & cons
- The de facto standard for metrics in Kubernetes
- Pull model means no agent pushing to you
- Free and open source
- Long-term storage needs an extra component
- PromQL takes time to learn
- Not built for logs or traces
Our verdict on Keycloak
The serious open-source answer to Auth0. Budget for the operations, because the licence saving is not free.
Our verdict on Prometheus
Pair it with Grafana and you have a complete metrics stack. Plan for long-term storage before you need it.