Parallels Workstation is described as '+ Professional-grade Virtualization for PCs: Simultaneously run a wide variety of Windows versions, Linux distributions, web stacks, database configurations, and multi-tier cloud environments on a single PC with the power and performance you need for web development, QA' and is an app in the Network & Admin category. There are more than 10 alternatives to Parallels Workstation for a variety of platforms, including Windows, Linux, Mac, Android and BSD. The best alternative is VirtualBox, which is both free and Open Source. Other great apps like Parallels Workstation are QEMU (Free, Open Source), VMware Workstation Pro (Paid), VMware Workstation Player (Free Personal) and KVM (Kernel-based Virtual Machine) (Free, Open Source).
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.
KVM (for Kernel-based Virtual Machine) is a full virtualization solution for Linux on x86 hardware containing virtualization extensions (Intel VT or AMD-V). It consists of a loadable kernel module, kvm.
Parallels Desktop gives Mac users the ability to run Windows, Linux or any other operating system and their critical applications at the same time as macOS. Parallels Desktop is optimized for Intel and Apple M1 chip.
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.