File Sync and Share

Dropbox

Online file hosting service offering cloud storage and file synchronisation.

http://dropbox.com/

Box

Online file sharing and content management service focused on business.

http://box.com/

SugarSync

Cloud file synchronisation service with a focus on backups.

http://sugarsync.com/

Google Drive

File storage and synchronisation service operated by Google.

https://www.google.com/drive/

B2Drop

Secure data exchange and cloud storage service focused on research. Currently in beta.

https://www.eudat.eu/services/b2drop

Resilio (formerly Bittorrent Sync)

Proprietary peer-to-peer file synchronisation software available on multiple platforms.

https://www.resilio.com