OpenLDAP - OpenLDAP Software is an open source implementation of the Lightweight Directory Access Protocol.
Keycloak - Open Source Identity and Access Management for modern Applications and Services.
FreeIPA - FreeIPA is an integrated security information management solution combining Linux (Fedora), 389...
Shibboleth - standards based, open source software for web single sign-on across or within organizational...
389 Directory Server - Enterprise-class open source Linux LDAP server.
CAS - Apereo CAS - Enterprise Single Sign On for the Web