mitmproxy is a fantastic tool and free. This is just marketing spam.
Why does team must-do-everything-in-the-terminal always come off as so religiously provocative and desperate? Not everyone is obsessed with their keyboard and feel like going through a huge learning curve to use basic tools, most of us prefer utilizing the mouse and GUIs.
People would have less problem if the submitted was an open source tool, GUI or not.
P.S. Terminal application does have tremendous advantage when you work on a headless server. I used mitmproxy and it's great. The ncurse'd interface isn't harder to use than that of a GUI.
I love MITMproxy and use it several times a day, but it is a bit to hard for newcomers go get their head around.
I also post a lot of different things to HN as long as I love it myself ;)