Dropbox syncs every file in its folder with all your devices—and Dropbox for Business shares files with your team just as easily.
“Dropbox Business lets us share relevant, up-to-date information with suppliers, contractors, and anyone else involved in a project. If we make changes to a file, everyone knows about it.”
We're paying $12.50/user/mo for Dropbox. There's a minimum of 3 users included so it's $4500/year.