Keycloak is an open-source Identity and Access Management (IAM) solution aimed at modern applications and services. Keycloak provides out-of-the-box authentication and authorization services as well as advanced features like User Federation, Identity Brokering, and Social Login.
Keycloak provides fine-grained authorization services as well. This allows you to manage permissions for all your services from the Keycloak admin console and gives you the power to define exactly the policies you need.