It allows you to use any standard SFTP client to connect and transfer file.
Editor: WAC SFTP (Secure FTP) Server for Windows NT/2000/XP is part of WAC Server product from Foxit Software.

It allows you to use any standard SFTP client to Connect and transfer file securely. All communications are encrypted with up to 256-bit strong encryption. Public-private key authentication is also supported. Tested with popular FREE clients including WinSCP, FileZilla, and PSFTP. Please choose SFTP protocol on SSH2 to connect. WAC Server allows most flexible access control, administrators can config access control for users, groups, or defaults. Anonymous access can also be enabled. Free evaluation copy allows 5 connections before restarting WAC Server. WAC Server also contains a full featured SSH server as well as telnet server, so you can also use SSH/telnet clients to connect to your server and get access to Windows command prompt. A collection of command prompt applications like File Explorer, Registry Editor are also bundled within this very affordable server package.

You can enjoy it in .com you can free download WAC Server Manager 1.4 now.