File Sever W/ Desktop Sync

We want to build a file server in our office - either Windows or Linux (doesn't make a difference to us).

We have a lot of satellite offices, and want to have certain computers have access to specific files/folders on the fileserver.

The catch is this... we would like some of our satellite computers to "sync" with the files/folders on the fileserver.

For example, a developer who is constantly working with a particular client, will always want his/her files to sync up with what is on the server.

The developer will want to work with a local copy of the files, and once finished, will upload them to the file server.

A few days go by, and there is a possibility the fileserver has additional information for that client. The developer would then want to download the changed files from the fileserver.

The benefit of working with local files, is that it is quicker to make changes. We can always leave the desktop on overnight to sync between the fileserver and the desktop.

Any suggestions what to look into here?

All of our desktops are on Windows, so we would need a windows application that has this functionality.

Rsync seems to be the closest thing I've found so far.