Agena is a minimal Gemini server written in CHICKEN Scheme. It
is designed to be used behind a TLS tunnel like stunnel or
relayd.
Note: I am no longer working on this software and I recommend that you do not use it. The Gemini protocol is vague and unfinished. I don't know whether this or any Gemini server can be said to correctly implement the protocol.
Generally speaking, I think Gemini may be a mistake. I'm now serving the content that I used to have on Gemini on the Web, as simple XHTML. That, not Gemini, is what I recommend if you want a simple, text-oriented browsing protocol.