FTPSync.pl is a powerful, cross-platform backup and synchronization application designed to automate transferring files from one FTP server to another. It supports FTP and FTPS, and has the ability to resume interrupted transfers and automatically detect and recover from broken connections. It also has a built-in scheduler, allowing you to set up recurring backups and synchronizations. It's a great tool for backing up websites, and can be used to transfer files between servers or between a local machine and a server. FTPSync.pl has an easy-to-use GUI, and the script can be customized to fit the needs of the user. It's a great tool for anyone needing to keep their files synchronized across multiple servers.
Discontinued Last commit 3d05473 on September 3, 2015. See https://github.com/timshannon/freehold
FlowCloud discontinued due to storage and maintenance issues. Read more here: https://flowcloud.xyz/why.html
Discontinued site no longer available
Discontinued It appears that the service is no longer updated since 2012 and the iPhone app is no longer available. You can still register new accounts and the website seems to work.
Discontinued "The Syncany core team is on hiatus for an indefinite period of time". See https://github.com/syncany/syncany