What are some alternatives?
When comparing Proxmox Virtual Environment and VMmanager, you can also consider the following products
oVirt - oVirt is a virtualization management application.
Virtualizor - Virtualizor is a powerful web based VPS Control Panel.
OpenStack - OpenStack software controls large pools of compute, storage, and networking resources throughout a datacenter, managed through a dashboard or via the OpenStack API.
vSphere - Get started with VMware vSphere editions, the world’s leading server virtualization platform and the best foundation for your apps, your cloud, and your business.
vSphere Hypervisor - Get a free vSphere Hypervisor by VMware to consolidate your applications and virtualize your servers. Learn how to optimize your server’s performance
Archipel - Archipel is a solution to manage and supervise virtual machines.