Syncthing vs Unison
A side-by-side comparison of two self-hosted file sync & storage options — licensing, setup difficulty, resource needs, and what each one replaces.
Syncthing
Continuous peer-to-peer file synchronization
VS
Unison
Bidirectional file synchronizer with conflict detection
| Feature | Syncthing | Unison |
|---|---|---|
| Deploy effort | ≈5-minute setup | Read-the-docs project |
| Health score | 100 · Excellent | 88 · Excellent |
| Category | File Sync & Storage | File Sync & Storage |
| License | MPL-2.0 | GPL-3.0 |
| Language | Go | OCaml |
| Setup difficulty | Easy | Medium |
| Min. RAM | 128 MB | 64 MB |
| Deployment | docker, binary, bare-metal | bare-metal, binary |
| GitHub stars | ★ 88,884 | ★ 5,493 |
| First released | 2014 | 1999 |
| Replaces | Dropbox, Resilio Sync | Dropbox |
What are Syncthing and Unison?
Syncthing
Syncthing is a continuous file synchronization program that syncs files between two or more devices directly, without a central server. It is ideal for individuals who want private, serverless sync across their own machines. It is distributed as a single binary and also runs well in Docker.
- Fully decentralized peer-to-peer sync
- TLS-encrypted transfers
- No cloud account required
- Cross-platform with mobile apps
Unison
Unison is a mature bidirectional file synchronization tool that reconciles changes made independently on two replicas. It detects conflicts, preserves both versions, and works over SSH for secure remote syncing.
- True bidirectional sync
- Conflict detection
- Works over SSH
- Cross-platform replicas
Syncthing vs Unison: key differences
Syncthing is written in Go, while Unison is built with OCaml. Licensing differs — MPL-2.0 for Syncthing versus GPL-3.0 for Unison. Unison is the lighter option, starting around 64 MB of RAM against 128 MB for Syncthing. Unison is the more established project (first released 1999), while Syncthing arrived in 2014. Syncthing has the considerably larger community, at 88,884 GitHub stars versus 5,493. Syncthing lists first-class Docker deployment; Unison does not.
Why pick each one
Choose Syncthing if…
- No central server needed
- Very private by design
- Lightweight and reliable
Watch out for
- No web file browsing
- Not a sharing platform
Choose Unison if…
- Very reliable
- Fine-grained control
Watch out for
- Dated GTK interface
- Version matching between hosts
Frequently asked questions
Is Syncthing or Unison better?
Syncthing is the stronger all-round pick: it has both the larger community and the simpler easy setup. Consider Unison if its specific feature set fits your needs better.
Are Syncthing and Unison free and open-source?
Yes. Syncthing is licensed under MPL-2.0 and Unison under GPL-3.0. Both can be self-hosted at no software cost.
Can I run Syncthing and Unison with Docker?
Syncthing: yes. Unison: check the project docs for container support.
Which is lighter on resources, Syncthing or Unison?
Unison has the smaller minimum footprint at 64 MB of RAM, compared to about 128 MB for Syncthing. Real-world usage depends on library size, user count, and enabled features.