What Java FTP client library should I use? [closed]
Check out Apache commons-net, which contains FTP utilities. Off the top of my head I'm not sure if it meets all of your requirements, but it's certainly free!
ftp4j is the best one, both for features and license:
Yes, EnterpriseDT's edtFTPj is stable (first released in 2000), has all the features you might need, and is open source as well.
It's used in a bunch of open source projects (as well as in many commercial projects), and is acknowledged to be one of the fastest client libraries around.
As another poster noted, if you do wish to upgrade to SFTP and/or FTPS, it is a simple upgrade path with very few code changes required.