"Keycloak: The Identity Layer You Own — Free Under Apache-2.0, Expensive to Operate"
"Keycloak is the leading open-source identity and access management platform — Apache-2.0, no per-user fee, backed by Red Hat. This 5,000-word teardown covers what it actually delivers, why running it is an infrastructure project, the high-availability trade-offs, and exactly where your users' credentials and sessions go."