Keycloak: Open-Source Identity and Access Management
In Keycloak nothing made sense to me until I got myself familiar with OAuth 2.0 and OpenID Connect.Keycloaks documentation seems vast, but isn't. There is also no way to search inside their documentation. It's a pity.A better documentation is contained in the administration web ui itself. There are so many "hints" and tooltips for almost every option there is. It really helped me a lot.Keycloak is good software. It never failed for me. Even upgrading from 7.x.x to 16.x.x somehow just worked.Yes, their docker image is fat, but it's also very flexible. Now that they are basing Keycloak on Quarkus instead on Wildfly, the docker image should shrink in size.    quay.io/keycloak/keycloak   18.0.0                      a6bd0f949af0   15 hours ago   562MB
    quay.io/keycloak/keycloak   18.0.0-legacy               421e95f49589   46 hours ago   753MB

ok, still big :).Beware: they aren't using Docker Hub anymore. Newer versions are on Quay only (https://quay.io/repository/keycloak/keycloak).I'm happy with Keycloak. Also nice folks around Keycloak.