CasaOS vs ZimaOS: which is better for an old PC home server?

Side by side

CasaOS

CasaOS isn't an operating system in the usual sense. You install Debian or Ubuntu first, then run one command, and CasaOS adds a clean web dashboard and an app store. Apps like Jellyfin, Nextcloud, or a file browser install with a click, and each one runs as a Docker container behind the scenes.

The install command from the CasaOS GitHub page is:

curl -fsSL https://get.casaos.io | sudo bash

Because it sits on top of a normal Linux system, you can still do anything Linux can do: install other software, mount drives however you like, or skip the dashboard and use the command line. It also runs on ARM boards like the Raspberry Pi, which ZimaOS doesn't.

The catch is development. The main CasaOS release hasn't changed since version 0.4.15 in December 2024. IceWhale hasn't announced an end of life, and its app store was still getting updates in 2026, but the company's attention has clearly moved to ZimaOS. CasaOS still works. I just wouldn't expect new features.

ZimaOS

ZimaOS grew out of CasaOS and looks a lot like it, but it's a complete operating system. You write it to a USB stick, boot the PC from it, and it takes over the drive you pick. It's built around being a NAS, a box that stores and shares files for the house, with the app store on top.

• Storage: RAID across several drives, file shares with their own user accounts and permissions, and a built-in 3-2-1 backup feature.
• Apps and VMs: the same style of one-click Docker apps, plus the option to run virtual machines.
• Managed system: the underlying Linux is locked down and updated as a whole. That's good for stability, but you're not meant to tinker with it the way you can on Debian.
• Price: since version 1.5 in September 2025, there's a paid Plus edition. As of September 2026, IceWhale's pricing page lists the free version at up to 4 disks and 3 users, with Plus at $29 for a lifetime license. Four disks is more than most old PCs can hold anyway.

To install it, the PC needs to start in UEFI mode with Secure Boot turned off, and at least 25 GB of storage for the system. Back up anything on the target drive first. ZimaOS erases it.

Which suits an old PC?

• A PC from about 2012 on, used mainly for file storage and a few apps: ZimaOS. It's the more complete package, and the storage tools are the reason to pick it.
• An old PC that only boots in Legacy BIOS mode: CasaOS on Debian. ZimaOS needs UEFI.
• A Raspberry Pi or other ARM board: CasaOS.
• You want to learn Linux along the way: CasaOS on Debian, since you have a normal system underneath to explore.

Either way, the hardware advice is the same as for any home server: 8 GB of memory if you can, an SSD for the system, wired Ethernet, and a PC that doesn't burn much power sitting idle. A used mini PC is hard to beat.

Try them first in a virtual machine

That's how I tried both. If you already have Proxmox or VirtualBox, create a VM, install one, click around for an evening, and delete it if you don't like it. IceWhale publishes instructions for installing ZimaOS on Proxmox from its ISO, and CasaOS goes on a small Debian VM with the one command above.

Keep in mind that a VM won't show you how either one handles your real drives. Once you've picked, install it on the actual PC before you trust it with anything important, and keep a backup of your files somewhere else.

When you outgrow them

Both are fine places to start, but they're built around one computer running one set of apps. At some point you may want snapshots before risky changes, separate systems that can't affect each other, or several machines working together. That's when people usually move to:

• Proxmox, which runs many separate virtual machines and containers on one PC. It's what I use, on a three-node cluster of mini PCs.
• Debian or Ubuntu with Docker Compose, which is what CasaOS does behind its dashboard, minus the dashboard.
• TrueNAS, if storage is the main job and you want ZFS protecting several big drives.