Awesome
FTP Server (swiftp)
<a href="https://f-droid.org/packages/be.ppareit.swiftp_free/" target="_blank"> <img src="https://f-droid.org/badge/get-it-on.png" alt="Get it on F-Droid" height="80"/></a> <a href="https://play.google.com/store/apps/details?id=be.ppareit.swiftp" target="_blank"> <img src="https://play.google.com/intl/en_us/badges/images/generic/en-play-badge.png" alt="Get it on Google Play" height="80"/></a>User documentation: see http://ppareit.github.io/swiftp/
Developer documentation: see file HACKING