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Backup · head to head

Kopia vs Storj

Kopia logo

Kopia

Backup

Open source deduplicating backup with client side encryption and a repository on almost any storage

From
Free
Rated
-
Full reviewWebsite
Storj logo

Storj

File Storage

S3-compatible object storage distributed in encrypted pieces across independently operated nodes

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Kopia space is only reclaimed when maintenance runs, and in a shared repository full maintenance is owned by one client, so if that machine goes away the repository grows for ever while every backup still reports success.; Storj billing includes a per segment charge and every object consumes at least one segment, so a bucket holding millions of small files can cost several times what the four dollar per terabyte headline implies.
  • They diverge on capability: Kopia covers Content defined chunking, Storj covers Erasure coded distribution.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Kopia and Storj actually diverge.

Attributes where Kopia and Storj differ
AttributeKopiaStorj
Pricing modelOpen source, no licence feePer terabyte per month
PlatformsLinux, macOS, Windows, DockerWeb, API, Linux, macOS, Windows
CategoryBackupFile Storage

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Kopia

  • Content defined chunking
  • Global deduplication
  • Pack blobs
  • Desktop and command line
  • Repository verification

Only in Storj

  • Erasure coded distribution
  • S3-compatible gateway
  • Native uplink access
  • Object Lock and versioning
  • Storj Select

Both cover

  • Client side encryption

What people use each for

The jobs each tool is most often brought in to do.

Kopia

  • Backing up laptops and workstations to cheap object storage with a desktop interface rather than a cron jobnot Storj
  • Deduplicating backups of several similar machines into one repository so common content is stored oncenot Storj
  • Replacing a chunk based tool whose per object charges made a cheap bucket expensivenot Storj
  • Keeping an encrypted offsite copy where the storage provider must never be able to read the contentsnot Storj

Storj

  • An offsite backup or archive target where the data is large, written once and occasionally restorednot Kopia
  • Serving large media files internationally without paying hyperscaler egress ratesnot Kopia
  • Storing data where the objection to AWS, Azure or Google is jurisdiction and concentration rather than costnot Kopia
  • A second, independent copy of a dataset that already lives in a hyperscaler bucketnot Kopia

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Kopia

  • Space is only reclaimed when maintenance runs, and in a shared repository full maintenance is owned by one client, so if that machine goes away the repository grows for ever while every backup still reports success.
  • The repository format has changed across versions and mixing client versions against one repository is discouraged, so a fleet must be upgraded together rather than machine by machine.
  • There is no central orchestration or reporting for many machines, so monitoring a fleet means building your own alerting around exit codes.
  • Restoring many small files is slower than the backup was, because content must be reassembled from pack blobs, and this is rarely tested until the day it matters.
  • Encryption is client side with no escrow, so a lost repository password means the data is unrecoverable and there is no vendor to appeal to.

Storj

  • Billing includes a per segment charge and every object consumes at least one segment, so a bucket holding millions of small files can cost several times what the four dollar per terabyte headline implies.
  • Reconstructing an object requires responses from dozens of independent nodes, so time to first byte is noticeably higher than a centralised bucket and it is a poor fit behind a latency sensitive read path.
  • Performance depends on the mix of node operators serving you at that moment rather than on a datacentre you can raise a ticket against, so slow reads are diagnosed statistically rather than fixed.
  • The hosted S3 gateway terminates encryption on Storj infrastructure, so using the convenient access path gives up the end to end encryption that is the main architectural argument for the service.
  • The S3 gateway is compatible rather than identical, so tools that lean on less common API calls, multipart edge cases or unusual header behaviour need testing before you commit a workload to it.

Pricing, plan by plan

Kopia

Free
  • KopiaFree
    • Full functionality, no data limit
    • Desktop application included
    • Any supported storage back end

Storj

Free
  • Free trialFree
    • 25 GB stored
    • 25 GB egress per month
    • No card required to start
  • Storj$4/month
    • 4 USD per terabyte stored per month
    • 7 USD per terabyte of egress
    • Per segment fee on top of stored volume

Which should you pick?

Choose Kopia if

  • You need content defined chunking.
  • You want to start without paying.
  • You work on Linux, macOS, Windows, Docker.
  • You also want global deduplication.
Kopia review

Choose Storj if

  • You need erasure coded distribution.
  • You want to start without paying.
  • You work on Web, API, Linux, macOS, Windows.
  • You also want s3-compatible gateway.
Storj review

Questions people ask

Is Kopia or Storj better?
Neither clearly leads. Kopia starts at Free and Storj at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Kopia or Storj?
Kopia starts at Free and Storj at Free.
Does Kopia or Storj run on more platforms?
Kopia runs on Linux, macOS, Windows, Docker. Storj runs on Web, API, Linux, macOS, Windows.
Can I use Kopia for free?
Both have a free tier, so you can try either at no cost before committing.
What is Kopia best used for?
Kopia is most often used for backing up laptops and workstations to cheap object storage with a desktop interface rather than a cron job, deduplicating backups of several similar machines into one repository so common content is stored once, replacing a chunk based tool whose per object charges made a cheap bucket expensive, keeping an encrypted offsite copy where the storage provider must never be able to read the contents. Of those, backing up laptops and workstations to cheap object storage with a desktop interface rather than a cron job and deduplicating backups of several similar machines into one repository so common content is stored once are not what Storj is typically brought in for.
What can Kopia do that Storj cannot?
Kopia covers Content defined chunking, Global deduplication, Pack blobs, Desktop and command line. Storj covers Erasure coded distribution, S3-compatible gateway, Native uplink access, Object Lock and versioning. Both handle Client side encryption.

Answered from the vendors’ own pages

Kopia: Is a partly corrupt repository still restorable?

Partly. Deduplication means one damaged pack blob affects every snapshot referencing its contents, but unaffected files still restore. Run verification regularly rather than assuming.

Storj: Why is my bill higher than four dollars per terabyte?

Almost always the per segment fee. Objects are split into segments and small files each consume one, so a few million tiny objects generate a segment charge that dwarfs the storage line.

Kopia: How does it compare with restic?

Similar guarantees, with packing that behaves better on per operation billing, a desktop interface, and compression enabled by default.

Storj: Can node operators read my data?

No. Files are encrypted client side and each operator holds only an erasure coded fragment, which is not a readable portion of the file.

Kopia: Do I need to run maintenance manually?

It is scheduled automatically by default, but you must ensure the client that owns full maintenance keeps running, otherwise deleted snapshots never free space.

Storj: Is there a minimum retention period?

No. You are billed for what you store while you store it, unlike several competitors that bill a ninety day minimum whatever you delete.

Kopia: Can several machines share one repository?

Yes, and that is where deduplication pays off, but they should run compatible versions and only one owns full maintenance.

Storj: Is it fast enough to serve a website from?

For large files with parallel reads, yes. For many small objects where time to first byte matters, put a CDN in front of it or use something centralised.

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