Dropbox - Online Sync and File Sharing

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.

Mega - Secure File Storage and collaboration

Box - Box offers secure content management and collaboration for individuals, teams and businesses, enabling secure file sharing and access to your files online.

FileRun - Beautiful, fast and reliable selfhosted file sharing and sync.