NAS operating systems turn a set of disks, or a spare PC, into a file server with shares, snapshots, apps and remote access.
This guide ranks them by how little they tie you to one vendor's hardware, what the licence costs over time, how cleanly data can leave, and whether the filesystem suits the job.
Vendors can pay for more visibility on this website, for example a higher place in a ranking or more room on a page. Commercial relationships can also affect which products we feature and how prominently. Every vendor link is marked the same, whatever the arrangement behind it. How that works.
In short
What NAS operating systems do
A NAS operating system manages disks and filesystems on a storage server, serves network shares and container apps through a web interface, and protects data with snapshots, RAID or checksums.
We ranked the 14 NAS operating systems on setup effort first, then total cost, then data export, then exit, then fit for the buyer. A separate rule reserves the first three places for challengers and moves the household names to place 4 and below. The reasoning behind the five tests, and behind having no score out of ten, is set out on the how we work page.
Ranked #1 of 14 in Best NAS Operating Systems in 2026.
Published pricingElsewhere
Unraid is described as an operating system for self-hosted servers and network-attached storage that runs on the buyer's own hardware. Its selling points are mixing drives of any size, passing a graphics card through for gaming or video editing, and Docker apps from hundreds of user-created Community Apps templates.
Licences are one-time: Starter, Unleashed and Lifetime. The 30-day trial needs no credit card, so a spare PC can prove the fit before any purchase.
What stands out
Mixed drive sizes
GPU passthrough
One-time licence
Where it costs you
The cheapest tier caps storage devices at 6 and bundles only one year of updates, so growth pushes you to a dearer licence.
The buy page names no CPU or RAM limits, so sizing a server means checking beyond the licence page.
Right for
Home builders reusing mismatched disks, wanting Docker apps and graphics passthrough.
Wrong for
Anyone who refuses to pay for any software licence.
Not stated by the vendorThree published one-time licence tiers, split by drive count and length of updates; 30-day trial, no card needed
Debian-based NAS software for homes and small offices
Ranked #2 of 14 in Best NAS Operating Systems in 2026.
Published pricingElsewhere
OpenMediaVault leans on Debian rather than a custom base, so updates follow standard package management and plugins extend the core. The feature list reads like a classic file server: web administration, volume management, S.M.A.R.T., link aggregation, Wake On LAN, IPv6, email notifications, sharing and shared-folder snapshots.
Nothing on the page describes an app store or support tier, which keeps expectations modest. It suits anyone comfortable maintaining a Debian machine.
What stands out
Debian base
Plugin extensions
Web administration
Where it costs you
The page links to licensing and credits pages but names no licence or country, so the legal basis stays unverified from this read.
Its stated audience is homes and small offices, which points to a narrower scope than larger estates need.
Right for
Small offices wanting a Debian-based file server with web administration and no licence fee.
Wrong for
Organisations that need a named vendor and a signed contract.
Not stated by the vendorDescribed as free software on the project page; no paid tier or plan structure is shown
OpenZFS storage from an appliance maker, with a Community Edition
Ranked #3 of 14 in Best NAS Operating Systems in 2026.
Pricing on requestNorth America
The Enterprise edition promises mission-critical storage with round-the-clock support, while Community Edition is the stated way to try the software. Hardware comes in V, M, F, R and H series plus Mini, with HDD, flash or hybrid layouts and an open API.
TrueCommand Cloud and TrueNAS Connect handle remote management. Because the open core licence is unnamed and quotes replace price lists, procurement needs more steps than a download.
What stands out
OpenZFS
Open core
Appliance lines
Where it costs you
The site shows no prices and its pricing page returned a 404, so budgeting means starting a sales conversation.
Open core means part of the code is visible, yet the page names no licence for it.
Right for
Teams wanting OpenZFS integrity checks and appliance-maker support behind file, block and object storage.
Wrong for
Hobbyists who expect published prices on the first visit.
United StatesEnterprise hardware priced on request through a quote form; Community Edition offered for testing
FreeBSD-based storage distribution that boots from USB or flash
Ranked #4 of 14 in Best NAS Operating Systems in 2026.
Pricing on requestElsewhere
XigmaNAS keeps the operating system off the data disks: the page says it can boot from flash media, SSDs, hard disks, a live CD or a USB stick, and run on virtually any hardware platform.
Storage choices include ZFS and software RAID 0, 1 and 5 with disk encryption, plus email reports. Partners listed are Jet Stream Systems Inc and Aspen Systems. The scope is deliberately plain storage, so extra services are your own work.
What stands out
FreeBSD base
ZFS and RAID
USB boot
Where it costs you
Only two sponsors are named, with no licence or country, so ownership and terms cannot be confirmed.
The capabilities listed are storage protocols and RAID, with no container or app catalogue mentioned.
Right for
Tinkerers wanting a lean FreeBSD file server that boots from a USB stick.
Wrong for
Anyone expecting a one-click app marketplace on top of storage.
Not stated by the vendorOpen-source distribution; the homepage lists no price, plan or paid tier
Btrfs-based NAS on openSUSE with Docker add-ons called Rock-ons
Ranked #5 of 14 in Best NAS Operating Systems in 2026.
Pricing on requestElsewhere
Rockstor ties its storage story to Btrfs: online capacity scaling, copy-on-write snapshots, checksums and compression come from the filesystem. Monitoring runs through a dashboard and SNMP, backups and replication are built in, and Docker-based Rock-ons add services.
Choosing it means choosing Btrfs, which suits those who already trust that filesystem. The 2026 copyright and live-looking links show a maintained site, yet active development remains unproven.
What stands out
Btrfs storage
openSUSE base
Rock-ons
Where it costs you
No licence and no country are stated, which leaves ownership and terms unclear.
The homepage cannot confirm recent development, so check release activity yourself before committing.
Right for
Linux users who prefer Btrfs snapshots and replication between two NAS boxes.
Wrong for
Teams needing a named company with a stated country.
Not stated by the vendorOpen-source project; the homepage shows no price, plan structure or licence name
Ranked #6 of 14 in Best NAS Operating Systems in 2026.
Pricing on requestElsewhere
HexOS leans on a partnership: the page states TrueNAS provides the underlying storage platform, so independence from a third party is limited.
What HexOS adds is a wizard, a dashboard for CPU, memory, storage and network stats with alerts, folder permissions and remote management through deck.hexos.com. The licence is per server and priced higher once Early Access ends. No free trial is mentioned.
What stands out
Setup wizard
Lifetime licence
TrueNAS underneath
Where it costs you
Buddy backups, replication and snapshots are marked beta access coming soon, so data protection is incomplete today.
Cloud backup is excluded from the lifetime licence as a metered service, adding a running cost.
Right for
Newcomers who want guided hardware checks and a one-time licence over TrueNAS storage.
Wrong for
Anyone needing a trial period or finished replication today.
Not stated by the vendorLifetime licence per server at an early-access rate, higher after that period ends; cloud backup metered separately
Docker-based personal cloud installed with a single command
Ranked #7 of 14 in Best NAS Operating Systems in 2026.
Open sourcePricing on requestAsia-Pacific
CasaOS treats storage as a side of a personal cloud: file management, network sharing, sync and backup between devices, plus remote access from outside the local network. Apps are Docker-based, with 20+ pre-installed and 50+ community-verified.
ZimaOS, described as the next-generation NAS OS powered by CasaOS, now carries the project forward. Its page does not state whether ZimaOS is sold alone or bundled, nor its licence.
What stands out
Apache-2.0
One-line install
Raspberry Pi ready
Where it costs you
An announced upgrade to ZimaOS suggests new work is moving to the successor.
The app store holds 20+ pre-installed and 50+ community-verified apps, fewer than larger stores.
Right for
Raspberry Pi owners wanting a licensed, open personal cloud with remote access.
Wrong for
Buyers wanting RAID tooling or snapshots as headline features.
ChinaApache-2.0 licensed project installed by script; no price or paid plan on the page
Volunteer-run server system that installs web apps in a few clicks
Ranked #8 of 14 in Best NAS Operating Systems in 2026.
Self-hostablePricing on requestElsewhere
YunoHost calls itself a non-profit technocritical project, developed and maintained by volunteers, with sponsors including nlnet, NGI and Gitoyen. That makes it a community effort without a company to sign a contract.
Hardware can be a Raspberry Pi, an old laptop or a VPS. Installation of applications takes a few clicks from its catalog, and a single portal serves users. Storage management beyond backups is not described.
What stands out
Volunteer-run
App catalog
VPS or Raspberry Pi
Where it costs you
The features listed cover apps, backups and a portal, with no RAID, snapshot or share management mentioned.
No legal entity, country or licence is named, only volunteers and sponsors.
Right for
Beginners wanting a low-effort server for apps and users on cheap hardware.
Wrong for
Anyone choosing mainly for disk pooling, RAID or snapshot management.
Not stated by the vendorNon-profit volunteer project; the homepage shows no price, plan or paid tier
Self-hosting platform with built-in reverse proxy, SSO and VPN
Ranked #9 of 14 in Best NAS Operating Systems in 2026.
Self-hostablePublished pricingElsewhere
Cosmos Cloud sits on top of an existing machine and concentrates on the front door: a reverse proxy issuing HTTPS certificates automatically, single sign-on with MFA, a built-in VPN and traffic filtering.
An app store of roughly 250 apps, backup and monitoring complete the package. Cosmos Pro, for multi-server clusters, starts at $16 a month. Because storage is not its focus, pair it with an actual NAS operating system.
What stands out
Commons Clause
Reverse proxy
SmartShield
Where it costs you
Commons Clause is the stated licence and the underlying one is unnamed, which limits clarity on reuse.
Its listed features concern access and security, not disk, RAID or share management.
Right for
Self-hosters who want login, HTTPS and VPN handled before exposing apps.
Wrong for
Those who need a complete operating system managing disks and arrays.
Not stated by the vendorCore platform under a Commons Clause licence; multi-server Cosmos Pro has published monthly pricing
Ranked #10 of 14 in Best NAS Operating Systems in 2026.
Self-hostablePricing on requestElsewhere
Umbrel packages home server use cases: photo backup, file storage, media streaming, local AI tools including Ollama and a Bitcoin node. FailSafe storage covers drive failures, and GPU detection helps apps.
Umbrel Home holds up to 4TB, Umbrel Pro four NVMe slots and up to 32TB, or you can supply drives. Personal and nonprofit use is permitted under the licence, but business use needs a conversation first.
What stands out
App Store
Noncommercial licence
Own drives or hardware
Where it costs you
The PolyForm Noncommercial licence means commercial use requires contacting the maintainers.
No company country appears, and the terms page returned a 404.
Right for
Households wanting photos, media and Home Assistant running through one-click installs.
Wrong for
Businesses planning commercial deployment without asking the maintainers.
Not stated by the vendorumbrelOS downloadable for own hardware; Umbrel Home and Pro hardware shown without prices
Start9's operating system for a personal server sold as hardware
Ranked #11 of 14 in Best NAS Operating Systems in 2026.
Self-hostablePricing on requestElsewhere
StartOS binds software to Start9's own box, so it scores lower on independence than OS-only projects. Premium Support is $200 a year, with the first year included with Server One and the RISC-V Router.
App choices skew towards Bitcoin and Lightning nodes, a Nostr relay and password management. The 0.4.0 release is a rewrite, which means early adopters should expect change. A NAS role is not described.
What stands out
Server One hardware
App marketplace
Bitcoin node apps
Where it costs you
Only the Server One hardware is named, and the page does not say whether StartOS runs elsewhere.
No open-source licence is stated and no price for the OS or Server One is shown.
Right for
People who want a sealed personal server for Bitcoin, Nostr and password apps.
Wrong for
Builders who plan to reuse their own old PC as the server.
Not stated by the vendorYearly premium support sold separately, first year bundled with Server One; OS and hardware prices not shown
Synology's NAS operating system with a long package list
Ranked #12 of 14 in Best NAS Operating Systems in 2026.
Pricing on requestElsewhere
DSM is described as the intuitive operating system that powers every Synology NAS. Its package list reads like a small software suite: Drive, Hybrid Share, Synology Tiering, SAN Manager and Synology High Availability sit beside the backup tools and office packages.
Breadth is the draw and lock-in is the price, since the page does not say how DSM is licensed or sold, and each extra package deepens dependence on one vendor.
What stands out
Synology hardware
Package centre
Backup suite
Where it costs you
DSM is tied to Synology NAS hardware, so you cannot run it on a spare PC.
No DSM prices appear, and nothing says whether it is bundled with hardware or licensed separately.
Right for
Offices wanting integrated backup, sync, mail and virtualisation on one vendor's hardware.
Wrong for
DIY builders who want to choose and replace their own machine.
Not stated by the vendorDSM page shows no price or licence terms and does not say if DSM is bundled with hardware
Linux-based NAS OS with snapshots, surveillance and virtualisation
Ranked #13 of 14 in Best NAS Operating Systems in 2026.
Pricing on requestElsewhere
QTS pairs file services with security features: a host-based firewall, malware scanning, secure remote connections, two-factor authentication and passwordless login.
Surveillance is licensed separately: QVR Pro sells perpetually from 8 channels up to 128, and QVR Surveillance offers 8 free channels expandable to 1,024 under subscription or perpetual terms. Totals rise with camera count, and the base operating system price is not shown.
What stands out
ext4 filesystem
Surveillance licences
Ransomware snapshots
Where it costs you
Whether QTS comes with the hardware is unstated, and no QTS price or currency is shown.
QVR Pro includes 8 channels and QVR Surveillance 8 free channels, so larger camera setups need further licences.
Right for
Offices combining NAS storage with camera recording and VMware or Hyper-V virtualisation.
Wrong for
Operators wanting an OS they can install on any spare PC.
Not stated by the vendorQTS price is not shown; surveillance add-ons are licensed by channel count, perpetual or subscription
Linux-based ADM with Btrfs snapshots and a 200-app store
Ranked #14 of 14 in Best NAS Operating Systems in 2026.
Pricing on requestElsewhere
ADM puts security tooling up front: a built-in firewall, ADM Defender, ClamAV, AES-256 folder encryption and file, folder and app isolation. Data tools include Cloud Backup Center with Amazon S3 and Backblaze B2, DataSync Center and MyArchive, and Docker deployments run through Portainer.
Snapshot Center covers Btrfs and iSCSI volumes. Because the page ties ADM to Flashstor, treat the operating system and device as one purchase.
What stands out
Btrfs snapshots
App Central
Camera licences
Where it costs you
The page does not state whether ADM is sold separately, so a hardware-free install looks unavailable.
Camera channels stop at four until licences are bought, up to a ceiling of 44.
Right for
Buyers who want Btrfs snapshots, antivirus and a modest app store on Asustor devices.
Wrong for
Anyone who needs ADM running on non-Asustor hardware.
Not stated by the vendorADM stated to come with the Flashstor NAS; separate sale not stated; extra camera channels need purchased licences
A NAS operating system manages disks and filesystems on a storage server, serves network shares and container apps through a web interface, and protects data with snapshots, RAID or checksums. The differences that matter are rarely in the feature list, so this is the order we would work through them.
01
Start with pricing transparency
The split is 3 published against 11 quoted. If you want to compare numbers first, start with Unraid, OpenMediaVault, Cosmos Cloud.
02
Decide how much the jurisdiction matters
These 14 vendors are established in 3 countries across 3 regions (Elsewhere 12, North America 1, Asia-Pacific 1). That decides whose disclosure law applies to what the vendor holds, wherever the servers are.
03
Consider whether you want the source
1 of these are open source: CasaOS. Hosting one yourself trades a subscription for maintenance.
NAS operating systems and the filesystem choice: ZFS, Btrfs or mixed drives
The filesystem sets how disks can grow and how corruption is caught, so decide it before the brand. TrueNAS and XigmaNAS are built around ZFS, which checks data with checksums and, in TrueNAS, self-heals. Rockstor and Asustor ADM lean on Btrfs, with Asustor's Snapshot Center allowing up to 256 snapshots per volume. QNAP QTS runs ext4 on a Linux kernel and relies on RAID and JBOD expansion.
Unraid takes another route and lets you mix drives of any size, adding disks over time. Pick the model that matches how you will buy drives: all at once, or one at a time as budget allows. A buyer planning a four-bay build in one go has different needs from someone adding a disk each quarter, and the vendors' pages do not hide that difference if you read the storage sections.
Write down whether you will buy drives together or one by one
Confirm snapshot limits per volume before relying on them
Check which filesystem the vendor names, not just which RAID levels
Vendor box or your own PC: where Synology DSM, QNAP QTS and Asustor ADM stop
Some systems only exist on the maker's hardware. Synology says DSM powers every Synology NAS, Asustor says ADM comes with its Flashstor NAS, and Start9 runs StartOS on Server One without saying it runs elsewhere. By contrast Unraid, OpenMediaVault and XigmaNAS target your own machine, CasaOS lists ZimaBoard, Intel NUC and Raspberry Pi, and Umbrel offers a download beside its Home and Pro boxes.
Tying software to a box can simplify support but removes the chance to move the OS onto a different machine when the hardware fails. Ask what happens to your licence and data if the device dies. For the vendor-box products, the pages read here do not explain how a replacement unit picks up your disks, so put that question to the seller before purchase, and keep a copy of important data elsewhere.
Ask whether the operating system can leave the vendor's box
List the hardware each candidate names as supported
Plan how the data would be read on a different machine
Headline prices hide limits. Unraid's Starter licence stops at 6 storage devices and one year of updates, while Lifetime removes the update expiry. HexOS sells a lifetime licence per server, yet cloud backup is excluded as a metered service and the price rises once Early Access ends. Umbrel's repository carries PolyForm Noncommercial, so business use needs the maintainers' agreement, and Cosmos Cloud uses a Commons Clause licence.
QNAP prices camera software by channel count, and Asustor sells extra camera licences beyond four channels. Read the licence file and the add-on price list, not just the download button. Totals for an office with cameras and cloud backup can look very different from a home build, and a licence that fits a household may not fit a company that wants to deploy the same software for clients.
Check device caps and update periods on each licence tier
Read the repository licence if the use is commercial
Price cameras and backup add-ons before choosing a platform
Apps versus storage: what CasaOS, Umbrel and YunoHost actually manage
Several products in this market are app platforms that borrow the NAS label. Umbrel lists Nextcloud, Immich, Jellyfin and Home Assistant with 300 more, Cosmos Cloud claims roughly 250 apps, Asustor over 200, and CasaOS 20+ pre-installed and 50+ community-verified. YunoHost lists installs, backups and a user portal but no RAID or snapshots, and Cosmos Cloud concentrates on proxy, login and VPN.
Storage-first systems such as TrueNAS, OpenMediaVault and Rockstor do the opposite and describe disks and snapshots before apps. Decide which half of the job you cannot do yourself, then check the other half is covered. A buyer who only wants shared folders and snapshots should not pay attention to app counts, and a buyer who mostly wants Jellyfin or Home Assistant should not pay attention to RAID levels.
Separate must-have storage features from nice-to-have apps
Check whether disk and snapshot management is described at all
Confirm the apps you need appear in the vendor's own catalogue
What goes wrong most often when buying NAS operating systems
Choosing Synology DSM or QNAP QTS for the software and forgetting that the box they run on cannot be swapped for a spare PC.
Treating Cosmos Cloud or YunoHost as a replacement for TrueNAS or OpenMediaVault when their pages list no RAID, snapshots or share management.
Trusting a HexOS or Unraid headline licence price without reading the drive cap, update period or excluded cloud backup.
Assuming open-source projects such as XigmaNAS, Rockstor or OpenMediaVault name a licence, owner and country, when their pages do not.
07
Frequently asked questions
8 answers
What are the best NAS operating systems in 2026?
First of 14 on this page is Unraid. Unraid runs on hardware you choose, accepts drives of any size and grows by adding disks, which makes it the most practical independent buy for a home server built from leftovers.
Lime Technology sells it as a one-time licence. The entry tier stops at 6 storage devices and one year of updates, and the buy page lists no CPU or RAM limits. The country behind it is not stated.
Which NAS operating systems publish their pricing?
Published pricing exists for 3 products on this page:
Unraid: Three published one-time licence tiers, split by drive count and length of updates; 30-day trial, no card needed.
OpenMediaVault: Described as free software on the project page; no paid tier or plan structure is shown.
Cosmos Cloud: Core platform under a Commons Clause licence; multi-server Cosmos Pro has published monthly pricing.
11 vendors do not print a price.
Is there a free NAS operating system?
Not among the products reviewed here: no vendor on this list has a free tier worth using.
Where are these NAS operating system vendors established?
Across 3 countries (Elsewhere 12, North America 1, Asia-Pacific 1):
Unraid: Not stated by the vendor.
OpenMediaVault: Not stated by the vendor.
TrueNAS: United States.
XigmaNAS: Not stated by the vendor.
Rockstor: Not stated by the vendor.
HexOS: Not stated by the vendor.
CasaOS: China.
YunoHost: Not stated by the vendor.
Cosmos Cloud: Not stated by the vendor.
Umbrel: Not stated by the vendor.
StartOS: Not stated by the vendor.
Synology DSM: Not stated by the vendor.
QNAP QTS: Not stated by the vendor.
Asustor ADM: Not stated by the vendor.
Which NAS operating systems are open source?
CasaOS.
Which NAS operating systems can you host yourself?
YunoHost, Cosmos Cloud, Umbrel, StartOS. The other 10 are hosted by the vendor only.
What should you use instead of Unraid?
Second is OpenMediaVault, which suits small offices wanting a Debian-based file server with web administration and no licence fee.. Third is TrueNAS, which suits teams wanting OpenZFS integrity checks and appliance-maker support behind file, block and object storage..
Who should not buy Unraid?
Anyone who refuses to pay for any software licence.. The cheapest tier caps storage devices at 6 and bundles only one year of updates, so growth pushes you to a dearer licence..
Sell NAS operating systems and missing from the ranking? Send us a line on what the product does and who buys it. Whether it is added is our decision, though commercial arrangements can also affect it, and the terms of a listing sit on the software advice page.
