VirtualBox, QEMU, VMware Workstation Pro, Parallels Desktop, VMware vSphere Hypervisor, WineBottler, Limbo PC Emulator, Windows Sandbox, VMware Workstation Player, KVM (Kernel-based Virtual Machine), VMware Fusion, Bochs, UCS Virtual Machine Manager, MobaLiveCD, VMWare Disk Mount, Mojopac, VMLite Workstation, Qemu Simple Boot, VMLite VBoot, GreenVBox, xhypervisor, FAUMachine, SmartOS, Virtual PC, GNURoot Debian, Parallels Workstation, VMLite XP Mode, VMLite MyOldPCs, MokaFive Player, VMX Builder, USBFastBoot are some alternatives to Portable Virtualbox.