QEMU

QEMU is a generic, open-source machine emulator and virtualizer. It can emulate a complete computer so that an operating system built for one architecture runs on a host with a different one, and it can also act as the device model behind hardware-assisted virtual machines.

It works in three main modes. Full-system emulation runs operating systems for any supported machine on any supported host architecture. User-mode emulation runs Linux or BSD programs compiled for another architecture. Virtualization mode runs KVM and Xen guests with near-native performance. Projects such as libvirt and libguestfs build on it.

QEMU is written in C and distributed under the GNU GPL, with some components under other licenses. The GitHub repository is an official mirror where pull requests are disabled; changes are submitted through the process described on the project website, and users are asked to rely on release tarballs from qemu.org. The project is a member of Software Freedom Conservancy.