Virt-Manager (Virtual Machine Manager) is a graphical desktop application for managing virtual machines through libvirt. It focuses on KVM and also supports Xen and LXC containers. It shows running virtual machines with live performance statistics, provides wizards to create machines and adjust their hardware, and includes an embedded VNC and SPICE viewer for the console. Accompanying tools include virt-install, virt-clone, virt-xml and virt-viewer. It manages both local and remotely accessible hypervisors and is distributed as a package by Linux distributions.
Virt-Manager is a community project: the site credits the Virtual Machine Manager contributors, and development takes place on GitHub under the GPL-2.0 licence. No single vendor owns it. It is locally installed software that connects to your own hypervisors, and the project site describes no hosted service. There is therefore no dependency on a foreign provider, but you rely on community support and on the packages of your Linux distribution.