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Unison

File Storage & Sync

A cross‑platform file synchronization tool that keeps two replicas of directories in sync, handling updates on both sides and working offline.

OCaml Latest v2.54.0 · 2mo ago Security brief →

Features

  • Works across POSIX (Linux/macOS/*BSD) and Windows systems
  • Synchronizes bidirectionally, merging independent updates and highlighting conflicts
  • Operates at the user level without kernel modifications or superuser privileges
  • Efficient bandwidth usage with rsync‑like compression for incremental transfers
  • Resilient to failures and supports repeat mode with filesystem monitoring

Recent releases

View all 1 releases →
v2.54.0 Breaking risk
⚠ Upgrade required
  • Support for external rsync is deprecated and may be removed in a future micro release.
  • Unison GUI support (lablgtk) may be abruptly discontinued with little notice; verify Mac GUI functionality as no active verification contributions exist.
Breaking changes
  • Unison no longer interops with versions before 2.52.0 and cannot read pre-2.52.0 archive files.
Notable features
  • Added desktop file
Full changelog

Changes in 2.54.0

Released 2026-05-01

  • Drop old wire protocol. Unison will no longer interoperate with
    versions before 2.52.0 and will no longer read pre-2.52.0 archive
    files.

  • Document that LLM output is unwelcome in the Unison project (code,
    issues, mailinglists, etc.).

  • Add desktop file.

Deprecation warning: support for external rsync will be removed;
this may happen even in a micro release.

DEPRECATION MAY HAPPEN WITH LESS THAN TYPICAL NOTICE:
lablgtk is difficult to use safely, and future maintenance is
unclear. Implementing the GUI without lablgtk requires more effort
than seems likely to happen. Thus, it is possible that support for
the unison GUI may end suddenly, on a particular platform, or on all
platforms -- even in a micro release. See
https://github.com/bcpierce00/unison/issues/1075

MAINTENANCE WARNING: No one is contributing to verify that the Mac
GUI continues to work -- so it might not. (So far, there are no
reports of serious, frequent failures.)

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Install & Platforms

Platforms
linux macos windows

Community & Support

Beta — feedback welcome: [email protected]