Cozystack and Proxmox VE are both open-source virtualization platforms, but they target different scales. Proxmox VE (AGPLv3) pairs KVM and LXC for SMB virtualization, labs, and single-tenant deployments under roughly 50 hosts. Cozystack (Apache 2.0) runs KubeVirt on Kubernetes, with a Tenant CRD for hard multi-tenancy, first-class managed databases and S3 object storage, and GPU support through the NVIDIA GPU Operator (passthrough or NVIDIA vGPU for VMs with your NVIDIA vGPU licence, HAMi sharing for pods). It suits service providers and regulated multi-tenant environments that have outgrown Proxmox’s design center. Ænix, which created Cozystack and co-maintains it, sells support and services, including Ænix Public Cloud Platform, a complete public-cloud product for hosting providers and regional clouds: customer portal, billing and service catalog.
Different scales. Different design centers. Both open source.
Pairs with: Ænix Public Cloud Platform — a complete public-cloud product for hosting providers and regional clouds outgrowing Proxmox’s design center: customer portal, billing and service catalog. Support tiers from $1,250 per 10 nodes per month.
| Proxmox VE | Cozystack |
|---|
| Licence | AGPLv3 | Apache 2.0 |
| Foundation | KVM + LXC | KubeVirt on Kubernetes |
| Multi-tenancy | Resource pools + role-based ACLs | Tenant CRD |
| Managed databases | Manual / community | First-class |
| S3 object storage | Manual | First-class |
| GPU | Passthrough | GPU Operator: passthrough or NVIDIA vGPU for VMs, HAMi sharing for pods |
| Best scale | <50 hosts, single-tenant | Multi-tenant, service-provider |
| Best for | SMB virtualization, labs | Service providers, regulated multi-tenant |
Where Proxmox VE is genuinely better
Simplicity is a feature, and the table above does not price it:
- One ISO, one afternoon. A working three-node cluster with HA and a web UI, installed by one person who has not read a platform-engineering book. Cozystack asks you to understand Kubernetes before you understand the platform.
- Proxmox Backup Server. Incremental, deduplicated, verified backups with single-file restore, built by the same vendor and integrated into the same UI. Velero plus per-database point-in-time recovery covers the same ground with more moving parts and more design work.
- Built-in ZFS and Ceph. Both are first-class, installable from the UI, and supported by the vendor. No separate storage decision on day one.
- Subscription cost. Proxmox subscriptions are priced per CPU socket per year: the Community tier sits in low three figures, and the tiers with support tickets cost more, but all are a different order of magnitude from any platform engagement.
- LXC where you want a container that behaves like a machine. Legitimately useful, and not something Kubernetes offers.
For a single-tenant, VM-mostly estate with a small team, Proxmox is the right answer and moving costs you more than it returns. Cozystack starts paying off where hard multi-tenancy, a catalogue beyond VMs, or per-tenant billing enter the requirements.
See Proxmox alternative for when moving beyond Proxmox makes sense, the Proxmox migration hub for the migration path, and Proxmox vs VMware vs Cozystack article for full comparison.
Ænix created Cozystack (CNCF Sandbox project) and co-maintains it with maintainers from other companies. On top of it we offer Ænix Public Cloud Platform, Ænix Private Cloud Platform and Ænix AI Platform.
Frequently asked questions
When should I choose Proxmox VE over Cozystack?
For teams running under roughly 50 hosts on single-tenant deployments, such as SMB virtualization or labs, Proxmox VE is the right answer. Its KVM plus LXC design is simpler to operate at that scale and tenancy level.
When does Cozystack start paying off?
Cozystack pays off above roughly 50 hosts and wherever hard multi-tenancy matters. Its Tenant CRD, KubeVirt foundation, and first-class managed databases and S3 storage are built for service providers and regulated multi-tenant environments.
How does multi-tenancy differ between the two?
Proxmox VE uses resource pools with role-based ACLs and pluggable auth realms, which works well for delegating within one organisation. Cozystack provides a Tenant CRD with nested tenants, per-tenant quotas and scoped audit, which is what an untrusted multi-customer or regulated environment needs.
What are the licences?
Cozystack is licensed under Apache 2.0, with no per-CPU or per-core licensing. Proxmox VE is licensed under AGPLv3. Both are open source.
Does Cozystack support GPUs better than Proxmox VE?
It goes further, but be precise about how far. Proxmox VE offers GPU passthrough, one card to one guest. Cozystack schedules GPUs through the NVIDIA GPU Operator and uses HAMi to share a card across container workloads, and passthrough or NVIDIA vGPU (where you hold the NVIDIA vGPU licence) is available for VMs. On MIG-capable cards, the GPU Operator also exposes MIG partitions to tenant Kubernetes clusters, which gives tenants that share a card hardware-level separation.
What does Ænix offer on top of Cozystack?
Ænix created Cozystack and sells support and services on top of it. Ænix Public Cloud Platform is a complete public-cloud product for hosting providers and regional clouds outgrowing Proxmox, with customer portal, billing and service catalog; support tiers start at $1,250 per 10 nodes per month (Basic, billed annually).
