Best NAS Operating System
If you want to build your own NAS instead of buying a Synology, the operating system you install matters more than the box. Four cover almost everyone. For free, integrity-first storage on ZFS, TrueNAS SCALE. For mixing any disk sizes and the easiest apps, Unraid. For a light, free NAS on modest hardware, OpenMediaVault. For storage plus virtualization on one machine, Proxmox. TrueNAS SCALE is the one I point most people to first.
Updated 2026-06-08 · by Jonathan Caruso
Top pick
TrueNAS SCALE
TrueNAS SCALE is free, built on ZFS, and gives you the strongest data protection you can get at home: end-to-end checksums, snapshots, and replication that catch and undo the silent corruption other systems never notice. The Linux-based SCALE line also runs Docker apps and VMs, so it is no longer just a storage box. For a NAS where the data actually matters, it is the default.
The options
TrueNAS SCALE
Free, open source (Community Edition)A free, ZFS-based NAS OS with snapshots, replication, Docker apps, and VMs.
Visit TrueNAS SCALE site- Runs on
- 8 GB+ RAM, more for ZFS caching, ECC recommended.
- Pick it if
- You want the strongest data integrity, for free, and can plan your pool.
Unraid
Paid: $49 / $109 / $249 one-timeA flexible parity array that mixes any disk sizes and has a huge app catalog.
Visit Unraid site- Runs on
- Modest, lower RAM baseline, boots from a USB stick.
- Pick it if
- You want to mix disk sizes, add one drive at a time, and run apps easily.
OpenMediaVault
GPL, freeA free, Debian-based NAS OS with a plugin system (omv-extras).
Visit OpenMediaVault site- Runs on
- Very light. Runs on a Raspberry Pi or an old PC.
- Pick it if
- You want a free, light NAS without ZFS's RAM appetite.
Proxmox VE
Free (optional paid enterprise repo)A hypervisor with native ZFS, for one box that both stores and computes.
Visit Proxmox VE site- Runs on
- More RAM for ZFS plus VMs.
- Pick it if
- You want storage and virtualization together rather than a dedicated NAS appliance.
How to choose
Start with your disks. If you have a matched set of drives and the data matters, TrueNAS SCALE on ZFS is the pick: checksums and snapshots protect it, and it costs nothing. If instead you have a pile of mismatched drives, or you expect to add storage one disk at a time, Unraid fits how homelabs actually grow, and its Community Applications catalog makes running services close to one click. That one decision settles it for most people; see TrueNAS vs Unraid for the full head-to-head.
Hardware and scope decide the rest. OpenMediaVault runs a capable NAS on very little, even a Raspberry Pi, when you want free and light without ZFS's RAM demands. Proxmox makes sense when the real goal is one machine that stores files and runs VMs, with a ZFS pool underneath; see Proxmox vs TrueNAS. Whichever you choose, plan the array before you buy disks. Run the numbers in the RAID and ZFS storage calculator so you know your real usable capacity and how many drives can fail.
The verdict
Run TrueNAS SCALE for most builds: it is free, ZFS gives you the strongest protection your data can get at home, and it now runs apps and VMs too. Choose Unraid if you want to mix disk sizes and add drives one at a time with the easiest app catalog, OpenMediaVault if you want free and light on modest hardware, or Proxmox if you want storage and virtualization on one box. If you have ruled TrueNAS out specifically, see our TrueNAS alternatives. Whatever you pick, plan the array first with the RAID and ZFS storage calculator.
FAQ
What OS is best for a NAS?
For most people, TrueNAS SCALE: it is free, runs on ZFS for the strongest data integrity, and now handles apps and VMs too. Pick Unraid instead if you want to mix disk sizes and add drives one at a time, or OpenMediaVault if you want a free, light NAS on modest hardware.
Is there a free NAS software?
Yes. TrueNAS SCALE and OpenMediaVault are both free and open source. TrueNAS is the heavier, ZFS-based option with the best data protection; OpenMediaVault is lighter and runs on almost anything, including a Raspberry Pi. Unraid is the main paid option, with one-time licenses from $49.
Is Synology still worth it over building your own?
Synology's DSM software is genuinely good and the hardware is turnkey, but DSM only runs on Synology boxes, and recent models have pushed drive-compatibility limits that annoy homelabbers. If you want to pick your own hardware and pay nothing for the OS, TrueNAS SCALE or Unraid on a mini PC or custom build gives you more for the money. See [Synology vs TrueNAS](/compare/synology-vs-truenas).
Which NAS OS is best for Plex or Jellyfin?
Any of them work. Unraid is the smoothest if you want the media server running on the same box, thanks to its app catalog. TrueNAS SCALE runs Plex or Jellyfin as an app and stores the library on a fast ZFS pool. Plan your storage layout first either way.
Can I install a NAS OS on any PC?
Mostly, yes. TrueNAS, Unraid, and OpenMediaVault install on standard x86 hardware, an old desktop, a mini PC, or a custom build. Unraid boots from a USB stick, TrueNAS and OpenMediaVault install to a small boot drive. OpenMediaVault also runs on ARM boards like the Raspberry Pi.
TrueNAS or Unraid for a first NAS?
If your drives are matched and the data is important, TrueNAS SCALE, because ZFS protects it and the OS is free. If your drives are mismatched, you want to grow a disk at a time, and you value the easiest app experience, Unraid is worth its one-time license. Read [TrueNAS vs Unraid](/compare/truenas-vs-unraid) before you commit.