Mutagen is a cross-platform, continuous, bidirectional file synchronization utility designed to be simple, robust, and performant. It is designed for use in remote development. It can synchronize locally or over SSH.
Mutagen is a very powerful tool that is still in early beta. It will almost certainly have unknown issues. It should not be used on production or mission-critical systems. Use on any system is at your own risk (please see the license).
That being said, Mutagen is a very useful tool and I use it daily for work on remote systems. The more people who use it and report issues, the better it will get!
|Windows||macOS/Linux||Code coverage||Report card|
For a quick usage guide that will cover 99% of your needs, please see the documentation site.
For platform-specific instructions and known issues, please see the platform guide.
Please see the FAQ.
Rather than provide a heavily biased feature comparison table, I'll just point out what I consider to be the unique and compelling features of Mutagen. Astute readers with knowledge of the file synchronization landscape can draw their own conclusions. I'd recommend users read this list so they know what they're getting.
- Mutagen is a user-space utility, not requiring any kernel extensions or administrative permissions to use.
- Mutagen only needs to be installed on the computer where you want to control synchronization. Mutagen comes with a broad range of small, cross-compiled "agent" binaries that it automatically copies to remote endpoints as necessary. Most major platforms and architectures are supported.
- Mutagen propagates changes bidirectionally. Any conflicts that arise will be flagged for resolution. Automatic conflict resolution is performed if doing so does not result in destruction of unsynchronized changes. Manual conflict resolution is performed by manually deleting the undesired side of the conflict. Conflicts won't stop non-conflicting changes from propagating.
- Mutagen uses the rsync algorithm to perform differential file transfers. These transfers are pipelined to mitigate the effects of latency. It stages files outside of the synchronization root and relocates them atomically.
- Mutagen is designed to handle very large directory hierarchies efficiently. It uses rsync to transfer directory snapshots when performing reconciliation so that snapshot transfer time doesn't scale linearly with directory size.
- Mutagen is robust to connection drop-outs. It will attempt to reconnect automatically to endpoints and will resume synchronization safely. It will also resume staging files where it left off.
- Mutagen identifies changes to file contents rather than just modification times.
- On systems that support recursive file monitoring (Windows and macOS), Mutagen effeciently watches synchronization roots for changes. Other systems currently use regular and efficient polling out of a desire to support very large directory hierarchies that might exhaust watch and file descriptors, but support for watching small directories on these systems isn't ruled out.
- Mutagen is agnostic of the transport to endpoints - all it requires is a byte stream to each endpoint. Support is currently built-in for local and SSH-based synchronization, but support for other remote types can easily be added. As a corollary, Mutagen can even synchronize between two remote endpoints without ever needing a local copy of the files.
- Mutagen can display dynamic synchronization status in the terminal.
- Mutagen does not propagate (most) permissions, but it does preserve permissions when updating files. The only permission propagated by Mutagen is executability or lack thereof. Any other permissions are left untouched for existing files and set to user-only access for newly created files. This is by design, since Mutagen's raison d'être is remote code editing and mirroring. Nothing in the current Mutagen design precludes adding permission propagation in the future.
- Mutagen attempts to handle quirks by default, e.g. dealing with case-(in)sensitivity, HFS's pseudo-NFD Unicode normalization, systems that don't support executability bits, or file names that might create NTFS alternate data streams.
- Mutagen has a best-effort safety mechanism that prevents propagation of synchronization root deletions. If Mutagen detects that one side of the synchronization session has been completely deleted, it will halt and refuse to propagate the removal, requiring the user to manually remove file on the other side and then use
mutagen resumeto continue the session. This detection is not perfect for directories since their deletion is non-atomic and Mutagen may see a large portion of the directory deleted while deletion is ongoing and propagate that deletion. That being said, Mutagen makes every effort to avoid synchronizing while concurrent changes are ongoing, instead waiting for the filesystem to stabilize.
You might have surmised that Mutagen's closest cousin is the Unison file synchronization tool. This tool has existed for ages, and while it is very good at what it does, it didn't quite fit my needs. In particular, it has a lot of knobs to turn, puts a lot of focus on transferring permissions (which can cause even more headache), and requires installation on both ends of the connection. I wanted something simpler, a bit more performant, and just a bit more modern (the fact that Unison is written in rather terse OCaml also makes it a bit difficult to extend or support on more obscure platforms and architectures).
Please see the build instructions.