Comparison

Kopia vs Arq

Kopia and Arq both land on Worth it.

Kopia

Worth it

Confidence: Medium

Free, fast, encrypted open-source backup that technical users and self-hosters love.

Worth it

Confidence: Medium

Buy if you're comfortable picking a storage provider and want cheap, encrypted Mac/PC backups you control.

Kopia versus Arq
Compare	Kopia	Arq
Verdict	Worth it	Worth it
Best for	Self-hosters and NAS owners	Mac/Windows users with existing cloud storage
Who it's not for	Non-technical users wanting set-and-forget backups . use Backblaze or Time Machine	Anyone wanting one-click, flat-rate unlimited backup
Privacy	Encrypted by default; one critical server RCE (CVE-2026-45695) fixed in 0.23.0 . run the latest version.^⁷	No known public vulnerabilities found in the sources reviewed.¹²
Support quality	Community forums only; no paid support	No support evidence found
Public sentiment	Overwhelmingly positive among self-hosters and technical users who praise its speed, with a minority reporting defaults and performance issues.^³	Forum users report years of reliable backups and built-in encryption, with occasional grumbling about pricing.¹³
Biggest gotcha	Patch to 0.23.0+ before running Kopia server; unauthenticated RCE (CVE-2026-45695)	Overage billing at $0.0059/GB monthly beyond 1TB; large media libraries add up fast¹¹

Non-technical users wanting set-and-forget backups . use Backblaze or Time Machine
Businesses needing vendor SLAs and support contracts
Anyone who won't promptly patch an internet-exposed Kopia server
Guess: enterprises needing certified compliance and managed backup