Pure-FTPd

Pure-FTPd is a free (ISC license) FTP Server with a strong focus on software security. It can be compiled and run on a variety of Unix-like computer operating systems including Linux, OpenBSD, NetBSD, FreeBSD, DragonFly BSD, Solaris, Tru64, Darwin, Irix and HP-UX. It has also been ported to Android.

History
Pure-FTPd is based on Troll-FTPd, written by Arnt Gulbrandsen while he was working at Trolltech from 1995 to 1999. When Gulbrandsen stopped maintaining Troll-FTPd, Frank Denis created Pure-FTPd in 2001, and it is currently developed by a team led by Denis.