Top Alternatives to Parallels Desktop

VirtulaBox is an open source software to run virtual systems on top of a physical system. Virtual systems are normally used for providing separate environment for each client sharing a single physical system.

Open Source Software for running Windows applications on other operating systems.

VMware Workstation is a hosted hypervisor that runs on x64 versions of Windows and Linux operating systems.

VMware Workstation Player, formerly VMware Player, is a virtualization software package for x64 computers running Microsoft Windows or Linux.

QEMU (short for Quick Emulator) is a free and open-source hosted hypervisor that performs hardware virtualization QEMU is a hosted virtual machine monitor.

VMware Fusion is a software hypervisor developed by VMware for Macintosh computers. VMware Fusion allows Intel-based Macs to run operating systems such as Microsoft Windows, Linux, NetWare, or Solaris on virtual machines, along with their Mac OS X operating system using a combination of paravirtualization, hardware virtualization and dynamic recompilation.

CrossOver is a Microsoft Windows compatibility layer available for macOS and Linux. This compatibility layer enables many Windows-based applications to run on macOS or Linux operating systems.

virt-manager, is a desktop-driven virtual machine manager with which users can manage virtual machines.

Portable-VirtualBox is a free and open source software tool that lets you run any operating system from a usb stick without separate installation.

MobaLiveCD is a freeware that will run your Linux LiveCD on Windows thanks to the excellent emulator called "Qemu".

Wineskin Winery is a tool for Wineskin.

Bochs (box) is a portable IA-32 and x86-64 IBM PC compatible emulator and debugger mostly written in C++ and distributed as free software under the GNU Lesser General Public License.