cPanel - With its first-class support and rich feature set, cPanel & WHM has been the web hosting industry's most reliable, intuitive control panel since 1997.
Keycloak - Open Source Identity and Access Management for modern Applications and Services.
Webmin - Webmin is a web-based interface for system administration for Unix.
Zentyal - Linux directory, domain, mail, gateway and infrastructure server for SMBs.
Vesta Control Panel - – What I love about Vesta is that it's fast and easy to use
OpenLDAP - OpenLDAP Software is an open source implementation of the Lightweight Directory Access Protocol.