ioFTPD is a professional high performance Ftp Server for Windows. It has a wide range of flexibility through its tcl scripting extension. Features vfs, low resource, detailed user access limitation, siteop, open source, and huge range of user made scripts.
Reviewing 7.2.1 Beta (May 17, 2010)
Note the current 7.4.3 release is experimental only!not for production server,more details can be found here : http://www.flashfxp.com/.../showthread.php?t=14188
from the author(Yil) :
The OpenSSL port of ioFTPD is now available. It should function the same, but a lot has changed so let me know if you notice anything odd...
Reviewing 7.1.0 Beta (Feb 4, 2010)
io's still on top of things. Still hoping for a more "normal" gui to rival my #1 choice (RaidenFTPD) for home use, but nothing much on this front yet :/
In any case, for those who want the ultimate flexibility and the most amazing set of scripts, io is still the ONLY way to go. Closely followed by Raiden :P
Reviewing 7.0.3 (Nov 6, 2009)
It's meant to serve high load private ftp server,works well with terabyte of data and high speed connection backbone.I was tested it against Raidenftpd newest,ioFTPD gain double the speed that i've got on Raidenftpd.ioFTPD really fast but the only minus is there is no good nice GUI like serv-u or RaidenFTPD,to track down wrong configuration you just need to check the log,and if it stay persist,friendly forum user will help you out.
Reviewing 7.0.3 (Nov 2, 2009)
This is the best ftp server for windows-based boxes. However in my humble opinion this is not the best choice for home use, where gui is still preferable, simply because why would anyone bother with half-baked gui solutions like the one ioFTPD currently has.
So, well, this really IS a #1 server for windows-based boxes, but I would recommend using it for those servers that are managed remotely. For home use I choose RaidenFTPD, which is quite powerful and at the same time got a decent gui, which makes a home server WAY easier to manage.