kiss-ftpd
An FTP server that Keeps It Simple, Stupid.
It simply serves the specified directory over FTP, allowing reads and writes, and that's it!
If you are after a more complicated FTP server with all the bells and whistles, unFTP looks good.
Usage
usage: kiss-ftpd [options...] [ftp_directory] [bind_address]
-h, --help print this usage text
-V, -v, --version Show version number then quit
If ftp_directory not specified, defaults to current working directory
If bind_address not specified, defaults to 0.0.0.0:21
There is an example systemd unit in systemd/kiss-ftpd.service which runs it with minimal permissions
and as locked down as possible.
Many thanks to libunftp which did all the heavy FTP lifting.