VirtualBox is a powerful x86 and AMD64/Intel64 virtualization product for enterprise as well as home use. Not only is VirtualBox an extremely feature rich, high performance product for enterprise customers, it is also the only professional solution that is freely available as...
QEMU (short for "Quick EMUlator") is a free and open-source hosted hypervisor that performs hardware virtualization.
VMware Workstation Player builds on the industry leading foundation of Workstation Pro, and delivers a streamlined user interface for creating and running operating systems and applications in a virtual machine.
Portable-VirtualBox is a free and open source software tool that lets you run any operating system from a usb stick without separate installation. It unpacks and adjusts the paths and configuration of VirtualBox so it will run portably.Discontinued
It has not been updated since 2017 and does not work with any version of Virtualbox beyond v5.1.22.
Bochs is a highly portable open source IA-32 (x86) PC emulator written in C++, that runs on most popular platforms. It includes emulation of the Intel x86 CPU, common I/O devices, and a custom BIOS. Currently, Bochs can be compiled to emulate a 386, 486...
FAUmachine is a virtual machine, similar in many respects to VMWare[tm], QEMU or Virtual PC[tm]. What distinguishes FAUmachine from these other virtual machines, are the following features:Discontinued
Last update 07/07/2012. See http://www3.informatik.uni-erlangen.de/Research/FAUmachine/download.shtml#Release