Free open source alternative app list of Parallels Desktop :

VirtualBox

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 3.

FreeWindowsmacOSLinux

Others are looking for free open source alternatives of following apps:

Adobe Premiere Pro

Adobe Premiere Pro is a professional video editing software for film, TV, and web.

Acorn 7

Acorn 7 is a Mac image editor for editing photos and creating graphics.

AdGuard DNS

AdGuard DNS is a DNS-based service that blocks ads, trackers, and malicious websites.

Ad Blocker

Ad Blocker is a browser tool that removes intrusive ads and pop-ups from web pages.

AI & Machine Learning

Free open-source AI & machine learning tools.

AdGuard

AdGuard is a cross-platform ad blocker that filters web content and protects privacy.