Dropbox's desktop app for Mac syncs your Dropbox folder with the cloud and your other devices. Share files and work with them directly from Finder.

Key features:

Sync changes to files and folders everywhere, including dropbox.com and mobile.
Share links to photos, videos, large files and folders with anyone, even people without an account.
Right-click files to see version history or send them for signature.
Control who can access files and folders and what they can do.
Search files and see recent activity from the Mac menu bar.

Dropbox Basic is free with 2 GB of storage. Plus is $9.99 a month for one person with 2 TB and 30-day file recovery. Standard ($15 per user a month) and Advanced ($24 per user a month) add team features.