EnterpriseDT 

edtFTPnet/PRO offers a set of robust and powerful, easy-to-use components and controls that make transferring files using the FTP, FTPS, SFTP, SCP and HTTP/HTTPS protocols a breeze. All protocols are supported in a single component.

edtFTPnet/Free is one of the most popular .NET FTP client libraries available today. Robust, fast and with an extensive API, it provides a solid foundation for developers who require FTP functionality in their .NET applications. Full source code is included.