When comparing Parallels Desktop vs Oracle VirtualBox, the Slant community recommends Oracle VirtualBox for most people. In the question“What is the best Virtual Machine (VM) for developers?” Oracle VirtualBox is ranked 1st while Parallels Desktop is ranked 4th. The most important reason people chose Oracle VirtualBox is:
VirtualBox is available for free with source code available [here](https://www.virtualbox.org/browser/vbox/trunk). A "VirtualBox Extension Pack" that includes virtual USB 2.0, VirtualBox RDP & PXE boot support is available only under a commercial license. VirtualBox is available on Windows, Linux, OSX and Solaris.
Ranked in these QuestionsQuestion Ranking
Pro Easy to use
Parallels has an easy to learn and use UI. All important features are wizard based. It requires only a few clicks for the wizard to download and set up the latest Chrome OS, Windows or Linux build.
Pro Can run Windows apps as native OS X apps
Parallels has a "Coherence View" mode that allows running Windows applications as if they were native OS X apps. In this mode Windows is virtualized in background and Windows features like Jump Lists, Taskbar, Start Menu, etc can be embedded directly within OS X.
Pro Best-in-class gaming performance
Compared to other VMs, Parallels has the best gaming performance. Still, a good framerate can only be achieved with games that have very low resource requirements. A much better option for resource intensive games is dual booting Windows (via Boot Camp).
Pro Best integration ever
Pro Free, mostly open source and cross-platform
VirtualBox is available for free with source code available here. A "VirtualBox Extension Pack" that includes virtual USB 2.0, VirtualBox RDP & PXE boot support is available only under a commercial license. VirtualBox is available on Windows, Linux, OSX and Solaris.
Pro Can do snapshots
VirtualBox is capable of taking whole-system snapshots and writing them to a backing file.
Pro Works with Vagrant
Works with Vagrant, an awesome tool for managing and deploying virtual machine images.
Con Very expensive
Parallels upgrades are very expensive. Even if I bough several versions of Parallels I will switch back to free VirtualBox as they even "invented" the Pro version - mainly doubled the price you have to pay each year to have the software updated.
Con Can't import OVA files
OVA files are useful because they include all of its supporting files. Unfortunately, Parallels doesn't support these useful files.
Con Requires buying a new version of the software with each new OS X release
Chances are that the same version of Parallels won't work with different OS X releases, requiring a separate purchase of Parallels for each OS X version.
Con Home edition doesn't work with Vagrant or Docker Machine
Make sure you purchase the Pro edition (the subscription) if you need command-line access to the hypervisor.
Con Can't export OVA files
One you use parallel you get trapped into a proprietary format.
Can't share disk blocks on two unrelated virtual machines (KSM for disk) too.
Con Inferior performance
Apart from second-class performance in virtualization, there are some visual glitches with Windows 8.1 on Mavericks.
Con Confusing interface and lacking usability features
VirtualBox might be a bit confusing for beginners - it requires an understanding of a lot more technical details than other VMs.