Parallels Desktop!

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 Open Source Software under the terms of the GNU General Public License (GPL) version 2.

Official description: VMware Workstation Pro Lets You Run Multiple Operating Systems as Virtual Machines (including Windows VMs) on a Single Windows or Linux PC. VMware Workstation Pro is the industry standard for running multiple operating systems as virtual machines (VMs) on a single Linux or Windows PC. IT professionals, developers and businesses who build, test or demo software for any device, platform or cloud rely on Workstation Pro.

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.

Seamlessly run your favorite Windows applications and devices, on any Intel-based Mac. Built from the ground up for the Mac, VMware Fusion is the easiest way to switch to Mac—letting you bring all of your Windows applications with you, making the most of your Windows software investment, while providing the perfect safety blanket for the switch.

Windows compatibility on Mac and Linux with no Windows license.

The virt-manager application is a desktop user interface for managing virtual machines through libvirt. It primarily targets KVM VMs, but also manages Xen and LXC (linux containers). It presents a summary view of running domains, their live performance & resource utilization statistics. Wizards enable the creation of new domains, and configuration & adjustment of a domain’s resource allocation & virtual hardware. An embedded VNC and SPICE client viewer presents a full graphical console to the guest domain. »

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. It will not support bridged networking through the virtualbox network adapter as it is not installed.

Wineskin is a tool used to make ports of Windows software to Mac OS X. The ports are in the form of normal Mac application bundle wrappers. It works like a wrapper around the Windows software, and you can share just the wrappers if you choose.Best of all, its free! Make ports/wrappers to share with others, make ports of your own open source, free, or commercial software, or just make a port for yourself! Why install and use Windows if you don’t need to?

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, Pentium/PentiumII/PentiumIII/Pentium4 or x86-64 CPU including optional MMX, SSEx and 3DNow! instructions.Bochs is capable of running most Operating Systems inside the emulation including Linux, DOS, Windows® 95/98 and Windows® NT/2000/XP or Windows Vista. Bochs was written by Kevin Lawton and is currently maintained by this project. Bochs can be compiled and used in a variety of modes, some which are still in development. The 'typical' use of bochs is to provide complete x86 PC emulation, including the x86 processor, hardware devices, and memory. This allows you to run OS's and software within the emulator on your workstation, much like you have a machine inside of a machine. For instance, let's say your workstation is a Unix/X11 workstation, but you want to run Win'95 applications. Bochs will allow you to run Win 95 and associated software on your Unix/X11 workstation, displaying a window on your workstation, simulating a monitor on a PC. »

Deis is an open source PaaS that leverages Docker, CoreOS and Heroku Buildpacks to provide a private application platform that is lightweight and flexible.

MobaLiveCD is a freeware that will run your Linux LiveCD on Windows thanks to the excellent emulator called "Qemu".MobaLiveCD allows you to test your LiveCD with a single click : after downloading the ISO image file of your favorite LiveCD, you just have to start it in MobaLiveCD and here you are, without the need to burn a CD-Rom or to reboot your computer.

Using Wineskin technology, Porting Kit is a PaulTheTall.com app that can install games and apps compiled for Microsoft Windows® in Mac OS X. It has access to a server where we store WSI files for more than 300 games, which can be installed by any Porting Kit user.