What is Hypervisor and what types of hypervisors are there? Xen is a type-1 bare-metal hypervisor. Just as Red Hat Enterprise Virtualization uses KVM, Citrix uses Xen in the commercial XenServer. Today, the Xen open source projects and community are at Xen. Today, XenServer is a commercial type-1 hypervisor solution from Citrix, offered in 4 editions.