Univention Corporate Server is a pre-configured platform to operate and manage server applications and complete IT infrastructures free of charge. It is optimal to provide Microsoft Server-like services on the cloud or on premises, to run and operate corporate IT environments with Windows-, Mac-, and Linux-based clients and extend those with proven enterprise software, also on the cloud or on premises. Main features: Active Directory-like domain services compatible with Microsoft Active Directory; a mature and easy-to-use web-based management system for central user, groups, rights and infrastructure management; a scalable underlying concept suited for single server scenarios up to the management of 1000s of clients and servers for 1000s of users within one single UCS domain; an app center with single-click installation and integration of many business applications from 3rd parties and Univention; management capabilities to manage Linux- and UNIX-based clients; command line, scripting interfaces and APIs for automatization and extension. The complete source code of UCS is provided under an Open Source license. The software is tried-and-tested and regularly updated. UCS is free of charge as a Core Edition without functional limitations. Companies preferring guaranteed, professional support can subscribe to maintenance services for UCS. Further features: An integrated IP management (DNS, WINS, DHCP), file, printer + desktop management, Ubuntu Domain Join Assistant, AD Takeover allows the migration of a Microsoft AD to UCS via Samba. AD Connection either integrates UCS in an AD domain or allows automatic sync of the AD and UCS. The App Center provides further UCS components and numerous Open Source products from 3rd parties such as ownCloud, Nextcloud, Kopano etc., many of them Docker-based and integrated in UCS' central identity management. Hybrid cloud management for OpenStack and Amazon EC2; based on Debian GNU/Linux 9 (Stretch); single sign-on; system monitoring