edtFTPj is Open Source (LGPL) and can be freely embedded into
commercial applications. It supports a wide range of FTP commands, and
has been downloaded over 90,000 times.
See
http://www.enterprisedt.com/products/edtftpj/overview.html
We also have available a derivative product, edtFTPj/SSL, a secure
version of edtFTPj supporting FTPS (FTP over SSL). For more details
see
http://www.enterprisedt.com/products/edtftpjssl/overview.html
regards
Bruce Blackshaw
Enterprise Distributed Technologies
London
United Kingdom