Unison

File Storage & Sync

A cross-platform file synchronization tool for keeping two replicas of directories up‑to‑date across different hosts or disks

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OCaml Latest v2.54.0 · 1mo ago Security brief →

Features

Synchronizes files and directories between POSIX systems (Linux, macOS, BSD) and Windows
Handles updates on both sides, automatically propagates non‑conflicting changes and highlights conflicts
Operates as a user‑level program without requiring kernel modifications or superuser privileges
Optimizes bandwidth with rsync‑like compression for incremental file transfers
Resilient to failures and supports repeat mode with filesystem monitoring

Recent releases

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v2.54.0 Breaking risk 1mo

⚠ 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.)

View release on GitHub

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