Keycloak - Open Source Identity and Access Management for modern Applications and Services.
Spring Security - The Spring portfolio has many projects, including Spring Framework, Spring IO Platform, Spring Cloud, Spring Boot, Spring Data, Spring Security...
Auth0 - Auth0 is a program for people to get authentication and authorization services for their own business use.
CAS - Apereo CAS - Enterprise Single Sign On for the Web
JSON Web Token - JSON Web Tokens are an open, industry standard RFC 7519 method for representing claims securely between two parties.
Webroot - Webroot delivers multi-vector protection for endpoints and networks and threat intelligence services to protect businesses and individuals in a connected world.