OpenStack is a free and open-source software platform for cloud computing, mostly deployed as infrastructure-as-a-service (IaaS), whereby virtual servers and other resources are made available to customers.
License: Open Source
VMware vSphere Hypervisor is a robust, enterprise-grade virtualization solution with strong support and management tools, but comes with high licensing costs. In contrast, OpenStack offers a flexible and scalable open-source cloud computing platform, but may require more technical expertise to configure and maintain.