XCP-ng is an open-source virtualisation platform built on the Xen hypervisor. The project began in 2018 as a fork of Citrix XenServer and is aimed at organisations that run virtual machines on their own servers and want an alternative to proprietary hypervisors such as VMware. You install it from an ISO image on physical hosts. It offers live migration of virtual machines without downtime, scaling by adding hosts, and management through the Xen Orchestra web interface, an API or the command line. Documented paths exist for migrating from XenServer and VMware.
XCP-ng is developed by Vates, a French company based in Grenoble, and is a Xen Project incubation project hosted by the Linux Foundation. According to Wikipedia, the licence is GPLv2 and others. Because you install and operate it yourself, you decide where workloads and data run, for example inside the EU. The source code is open and can be inspected; Vates also sells commercial support.