The XDA piece on ZimaOS and FygoOS put a name on something builders have felt for a year: TrueNAS and Unraid are no longer the only DIY NAS operating systems anyone considers. Cheap x86 mini PCs, Docker-first workloads, and ZFS on Linux have widened the field enough that the right pick depends on the box, the drives, and how much time you want to spend on the OS. We tested eight NAS operating systems across four hardware profiles: a two-bay Synology-class mini PC, a HP MicroServer Gen10 Plus, a Beelink SER5, and a Raspberry Pi 5.
What to look for in a NAS operating system
The right NAS OS depends on which of these matter to you:
- Storage protection model (parity, ZFS, BTRFS, or single-drive)
- Hardware footprint and RAM floor
- App / container catalogue depth
- Backup, snapshot, and replication story
- UI polish for the family members who will also use it
- Update cadence and release stability
- Cost — free open source, paid license, or subscription
The eight NAS operating systems below cover most of the corners of that grid.
Quick comparison table
| App | Best for | Platforms | Free plan | Starting price | Rating |
|---|---|---|---|---|---|
| CasaOS | Beginner home lab | Linux | Yes | Free | Community favorite |
| TrueNAS Scale | ZFS at scale | Linux | Yes | Free | Enterprise-grade |
| Unraid | Mixed-drive parity | Linux | 30-day trial | $49 basic | Very popular |
| ZimaOS | Mini-PC container box | Linux | Yes | Free | Rising |
| FygoOS | Beginner with ZFS | Linux | Yes | Free | New in 2025 |
| OpenMediaVault | Debian purists | Linux | Yes | Free | Established |
| Proxmox VE | Hypervisor + storage | Linux | Yes | Free | Homelab standard |
| UmbrelOS | Self-hosted app store | Linux | Yes | Free | Slick app store |
The DIY NAS operating systems
1. CasaOS — Best for a first home lab
CasaOS is a lightweight NAS front-end that installs on top of a Debian or Ubuntu base. The pitch is a Jellyfin, Nextcloud, or Home Assistant box in under an hour. IceWhale keeps the app store curated and the dashboard clean, and the whole stack runs on a single-board computer.
Where it falls short: No native storage protection. Multi-user permissions are shallow. Update cadence is quarterly at best.
Pricing:
- Free: Fully open source, MIT license.
- Paid: None.
Platforms: Linux (Debian/Ubuntu/Raspbian). Runs on x86 and ARM.
Download: CasaOS
Bottom line: Start here if you have never run a NAS OS before and the workload is Docker apps first, storage second.
2. TrueNAS Scale — Best for ZFS-first builds
TrueNAS Scale is iXsystems’ Linux flagship — the ZFS-native NAS OS with first-class replication, dataset snapshots, and a Kubernetes apps layer. It is what most homelab builders end up on once the drive count passes four and the data starts to matter.
Where it falls short: RAM-hungry. Kubernetes apps churn between releases. Not a fit for boxes under 8 GB of RAM.
Pricing:
- Free: Full-featured community build.
- Paid: iXsystems enterprise licensing for hardware and support.
Platforms: Linux (Debian base).
Download: TrueNAS Scale
Bottom line: Pick if the array is at least four drives and ZFS is the goal.
3. Unraid — Best for mixed-drive parity
Unraid is the answer for anyone with a pile of drives bought at different times. Its parity model tolerates mismatched sizes and lets the array grow one drive at a time. Community Applications is the deepest third-party store in the NAS space.
Where it falls short: Commercial license. Single-drive parity by default (dual parity available at higher tiers).
Pricing:
- Free: 30-day trial.
- Paid: Basic $49 (six devices), Plus $89, Pro $129, or $249 lifetime unlimited.
Platforms: Linux (Slackware base, boots from USB).
Download: Unraid
Bottom line: Pick if the drives are mismatched and buying matched ones is not on the table.
4. ZimaOS — Best for small mini-PC builds
ZimaOS is IceWhale’s sibling project to CasaOS. Where CasaOS runs on top of an existing Linux install, ZimaOS is a full OS aimed at ZimaBoard, ZimaCube, and third-party x86 mini PCs. The UI is the closest anyone has come to a Synology-style experience on DIY hardware.
Where it falls short: RAID and multi-drive setups are minimal. Two-plus bays with parity are not the target.
Pricing:
- Free: Full OS.
- Paid: Optional IceWhale cloud services and hardware.
Platforms: Linux (Debian base). x86-64.
Download: ZimaOS
Bottom line: Pick for a single-bay or two-bay mini PC where the priority is a clean UI.
5. FygoOS — Best for beginners who want ZFS
FygoOS is the new entry that made everyone re-evaluate the space in 2025. Native ext4, BTRFS, and ZFS support without dropping to a terminal, an on-device AI photo layer, and a UI that looks a generation ahead of OMV.
Where it falls short: FygoOS is the international rebranding of fnOS, a Chinese-developer project whose predecessor had a security incident in early 2026 — do not expose the box directly to the internet. Community outside China is still small.
Pricing:
- Free: Base OS.
- Paid: None for the base OS.
Platforms: Linux. x86 and ARM.
Download: FygoOS
Bottom line: Pick if ZFS on beginner hardware is the appeal and the box lives behind a firewall.
6. OpenMediaVault — Best for Debian purists
OpenMediaVault is the long-standing Debian-based NAS OS that predates most of this list. Add Docker via omv-extras and it becomes a competent home NAS. The plugin ecosystem is where most of the interesting features live.
Where it falls short: UI is dated. Plugin drift between major releases can strand third-party extensions. No first-class parity story.
Pricing:
- Free: Fully open source.
- Paid: None.
Platforms: Linux (Debian).
Download: OpenMediaVault
Bottom line: Pick if you want a stable Debian base and are comfortable managing plugins.
7. Proxmox VE — Best for hypervisor plus storage
Proxmox VE is the hypervisor most homelabs settle on. KVM, LXC, and ZFS live in the same shell, and a NAS layer runs cleanly as a container or VM alongside game servers and Home Assistant. It is what people graduate to when a single-purpose NAS is no longer enough.
Where it falls short: Learning curve. Shares are set up inside a VM or container, not on the host itself. The web UI assumes you know what you want.
Pricing:
- Free: Community repository, full features.
- Paid: Enterprise subscriptions from around €115/CPU/year.
Platforms: Linux (Debian).
Download: Proxmox VE
Bottom line: Pick if the box needs to run VMs and containers on top of storage.
8. UmbrelOS — Best for a self-hosted app store
UmbrelOS started life as a Bitcoin node OS and has grown into a general self-hosted app store with the cleanest UX on this list. Nextcloud, Immich, Home Assistant, and a Bitcoin node are all a click away.
Where it falls short: Storage layer is thin. No parity, no ZFS defaults, no replication story. It is an app OS more than a NAS OS.
Pricing:
- Free: Fully open source.
- Paid: Optional Umbrel Home hardware.
Platforms: Linux. Runs on Umbrel Home, Raspberry Pi, and x86.
Download: UmbrelOS
Bottom line: Pick if the app store matters more than the storage story.
How to pick the right one
- If you want the simplest option: CasaOS or UmbrelOS.
- If you need serious storage: TrueNAS Scale or Unraid.
- If the hardware is a small mini PC: ZimaOS or FygoOS.
- If you already know Debian: OpenMediaVault.
- If the box also runs VMs: Proxmox VE with a storage VM on top.
- If you tried OMV and hated the plugin drift: ZimaOS or FygoOS for a small box, TrueNAS for a big one.
- On a Raspberry Pi: CasaOS or UmbrelOS. Skip TrueNAS Scale and Proxmox.
FAQ
What is the best free NAS operating system?
TrueNAS Scale for ZFS-heavy setups, CasaOS for beginners, and ZimaOS for mini PCs. All three are fully open source and cost nothing.
Is Unraid worth paying for?
If the drives are mismatched, yes — the parity model saves the cost in drives you do not have to replace. If the array is matched drives, TrueNAS Scale does the same job for free.
What NAS OS do most people use?
TrueNAS and Unraid still lead on install base, with CasaOS climbing quickly among beginners and ZimaOS gaining share on mini-PC builds. FygoOS is the newest entrant.
Can I run these on a Raspberry Pi?
CasaOS and UmbrelOS run well on a Pi 4 or Pi 5. FygoOS supports ARM. TrueNAS Scale and Proxmox are x86 only.
What is the best NAS OS for beginners?
CasaOS if the workload is Docker apps, ZimaOS if the priority is a Synology-style UI, and UmbrelOS if the app store matters most.
