QEMU

QEMU is a free and open-source virtualization system that lets you emulate a vast range of operating systems on your computer. It acts as a safe sandbox, allowing you to install, configure, and test different OSes—from legacy versions to cutting-edge builds—without affecting your main system. This is ideal for developers, IT professionals, and curious users who want to evaluate software compatibility, learn new environments, or find their perfect 'daily-driver' OS with zero risk. Run multiple virtual machines simultaneously for complex testing scenarios.