Nowadays, securing APIs is of paramount importance due to the interconnectedness of our world. Keycloak is an open-source tool that offers several security features, including authentication, authorization, and Single Sign-On. In this journal, we delve into the ways of protecting APIs with Keycloak. We investigate how to configure Keycloak with APIs and illustrate how it can be utilized to authenticate and authorize API requests. Additionally, we examine how to set up OAuth2/OpenID Connect integration and merge Keycloak with existing enterprise authentication systems. By employing Keycloak in API security, companies can enhance their overall security measures, reduce the possibility of data breaches, and provide a seamless user experience.