VMware vSphere Hypervisor is the new name for what was formerly known as VMware ESXi Single Server or free ESXi (often abbreviated to simply “VMware ESXi”). VMware vSphere Hypervisor is the free edition of the vSphere production line. It is licensed to only unlock the hypervisor functionality of vSphere, but it can be seamlessly upgraded to more advanced offerings of VMware vSphere. VMware vSphere is available in multiple editions, including several options specifically designed for small businesses.