Caddy is a powerful, enterprise-ready, open source web server with
automatic HTTPS written in Go.

This command line tool and associated Go package makes it easy to
make custom builds of the Caddy Web Server.

There is an rc(8) script in /usr/ports/www/xcaddy/files/caddy that
you can put in /usr/local/etc/rc.d/ if you want. The caddy-custom
port (/usr/ports/www/caddy-custom) can build a custom caddy for
you using xcaddy.