"cool-retro-term".
I'd only encountered this framework within one or two commercial products which were either inaccessible or out of date, so it was a happy realization that it now powers an open-source terminal emulator for Linux and Mac.
As someone who's still a beginner exploring the terminal (something of an backwards journey from the present), it's affirming and sating. The sincerity that must go into a project like this.