Keycloak - Open Source Identity and Access Management for modern Applications and Services.
CAS - Apereo CAS - Enterprise Single Sign On for the Web
Zentyal - Linux directory, domain, mail, gateway and infrastructure server for SMBs.
Auth0 - Auth0 is a program for people to get authentication and authorization services for their own business use.
OpenLDAP - OpenLDAP Software is an open source implementation of the Lightweight Directory Access Protocol.
Webroot - Webroot delivers multi-vector protection for endpoints and networks and threat intelligence services to protect businesses and individuals in a connected world.