Dropbox - Online Sync and File Sharing
Filestash - Filestash is a modern client for FTP, SFTP, S3, WebDAV, Minio,...
Mega - Secure File Storage and collaboration
Syncany - Syncany is an open-source cloud storage and filesharing application.
ownCloud - ownCloud is an open source project enabling businesses to host their own cloud storage while maintaining regulatory and compliance needs.
FTPSync.pl - FTPSync.pl is a PERL skript to synchronize a local directory tree and a remote FTP directory tree.