Keycloak vs Spring Security: What are the differences?
Keycloak: An open source identity and access management solution. It is an Open Source Identity and Access Management For Modern Applications and Services. It adds authentication to applications and secure services with minimum fuss. No need to deal with storing users or authenticating users. It's all available out of the box; Spring Security: A powerful and highly customizable authentication and access-control framework. It is a framework that focuses on providing both authentication and authorization to Java applications. The real power of Spring Security is found in how easily it can be extended to meet custom requirements.
Keycloak and Spring Security can be primarily classified as "User Management and Authentication" tools.
Spring Security is an open source tool with 3.63K GitHub stars and 3.2K GitHub forks. Here's a link to Spring Security's open source repository on GitHub.