Dropbox - Online Sync and File Sharing
FTPbox - FTPbox is an open-source application that allows you to synchronize your files to your own host...
Google Drive - Access and sync your files anywhere
ownCloud - ownCloud is an open source project enabling businesses to host their own cloud storage while maintaining regulatory and compliance needs.
Syncany - Syncany is an open-source cloud storage and filesharing application.
Freehold - An open, secure, and lightweight platform for your files and data.