JackAss is a VST plugin that provides JACK-MIDI support for VST hosts. Simply load the plugin in your favourite host to get a JACK-MIDI port. Each new plugin instance creates a new MIDI port.

JackAss sends the notes from the host to its JACK-MIDI port. It also exposes 50 parameters, which send a MIDI CC message when changed. One can use this to easily control external applications that accept JACK-MIDI input and possibly CC for automation (like Carla).

Additionally there's a JackAssFX plugin, which only exposes parameters to send as MIDI CC, in case you don't need MIDI/notes.