This is the syncthing project. The following are the project goals:

1. Define a protocol for synchronization of a folder between a number of collaborating devices. The protocol should be well defined, unambiguous, easily understood, free to use, efficient, secure and language neutral. This is the Block Exchange Protocol.

2. Provide the reference implementation to demonstrate the usability of said protocol. This is the syncthing utility. It is the hope that alternative, compatible implementations of the protocol will come to exist.

The two are evolving together; the protocol is not to be considered stable until syncthing 1.0 is released, at which point it is locked down for incompatible changes.

Take a look at the getting started guide.

There are a few examples for keeping syncthing running in the background on your system in the etc directory.

There is an IRC channel, #syncthing on Freenode, for talking directly to developers and users (when awake and present, etc.).

Building Syncthing from source is easy, and there's a guide. that describes it for both Unix and Windows.

As of v0.10.15 and onwards, git tags and release binaries are GPG signed with the key D26E6ED000654A3E (see http://syncthing.net/security.html). For release binaries, MD5 and SHA1 checksums are calculated and signed, available in the md5sum.txt.asc and sha1sum.txt.asc files.

The syncthing documentation is on the Github wiki.

All code is licensed under the GPL, v3 or later.