Even in the era of cloud-native computing and Kubernetes, virtual machines remain a critical part of enterprise infrastructure. Many workloads are not yet containerized, and some may never be, due to legacy application constraints, licensing limitations, or performance characteristics. VMs continue to provide strong isolation, predictable performance, and support for traditional operational models. As such, finding a robust, future-proof virtualization platform remains essential.
In this changing climate, three open source alternatives frequently emerge in conversations: Proxmox VE, OpenStack, and KubeVirt. Each offers a unique take on virtualization, but choosing the right one depends heavily on context and operational goals.
The Contenders
Proxmox VE
Proxmox Virtual Environment (VE) is a complete open source platform for enterprise virtualization, developed by Proxmox Server Solutions GmbH. Built on a foundation of Debian Linux, it integrates KVM for virtual machines and LXC for containers, managed through a clean web-based UI. Proxmox supports features like live migration, high availability clustering, software-defined storage (Ceph or ZFS), and integrated backup solutions. It has built a reputation for being easy to install, straightforward to manage, and relatively lightweight compared to other enterprise-grade solutions.
Proxmox appeals especially to small and medium-sized businesses or IT teams looking for a VMware-like experience without the associated complexity or licensing costs. Its documentation and community are active and accessible, helping teams ramp up quickly.
OpenStack
OpenStack is an open source cloud operating system originally started by NASA and Rackspace in 2010. It allows users to manage compute, storage, and networking resources via APIs and a dashboard, following an Infrastructure-as-a-Service (IaaS) model. It’s designed for large-scale, multi-tenant environments and supports a wide range of configurations and integrations.
While OpenStack is incredibly powerful and flexible, it is also notoriously complex to deploy and operate. It consists of many loosely coupled services (Nova, Neutron, Cinder, Glance, Keystone, etc.), which require significant operational expertise. It’s a strong choice for organizations that need cloud-scale capabilities, multi-tenancy, or have specific integration requirements, but it can be excessive for smaller environments or simple virtualization needs.
KubeVirt
KubeVirt is a relatively newer open source project that extends Kubernetes to support virtual machines alongside containers. It allows you to treat VMs as Kubernetes resources, benefiting from Kubernetes-native workflows, scheduling, and infrastructure-as-code practices. It was originally started by Red Hat as a way to bridge the gap between traditional virtualization and cloud-native development.
KubeVirt is best suited for organizations that are already deeply invested in Kubernetes and want to maintain VM-based workloads during their cloud-native transformation. It brings VMs under the same operational model as containers, making it possible to apply DevOps principles to legacy applications.
However, it requires strong Kubernetes skills and is less suited for teams unfamiliar with concepts like operators, persistent volumes, and cluster management. It also may not be ideal for long-lived, high-memory or high-IOPS VM workloads common in traditional environments.
Key Takeaways
While all three projects cover the core requirements of a modern virtualization platform, their suitability varies based on the organization’s size, maturity, and goals:
OpenStack was eliminated early due to its complexity and overkill for environments that don’t need hyperscale capabilities. While it’s incredibly powerful, it demands significant operational overhead.
KubeVirt shows great promise for cloud-native shops that want to bridge VMs and containers. However, it’s not a great fit for teams without solid Kubernetes know-how or those running persistent, legacy VM workloads.
Proxmox VE emerged as the most practical choice—especially for teams transitioning from VMware. It’s approachable, easy to manage, and supports a wide array of features that make migration and day-to-day operations simple and reliable.
Conclusion
If your organization is rethinking its virtualization strategy post-VMware, it’s critical to align the new platform with both your current capabilities and future direction. For most mid-sized IT teams or those looking for a straightforward, no-nonsense replacement, Proxmox hits the sweet spot: open source, mature, and easy to adopt.