Only one computer needs to be online for the sync to work. This is a good thing because your files never go to a third party. You don't have to trust Dropbox or

Only one computer needs to be online for the sync to work. This is a good thing because your files never go to a third party. You don't have to trust Dropbox or anyone else with your data. Plop it on a couple of servers and you're good to go.