zynjacku is JACK based, GTK (2.x) host for LV2 synths. It has one JACK MIDI input port (routed to all hosted synths) and one (two for stereo synths) JACK audio output port per plugin. Such design provides multi-timbral sound by running several synth plugins.
At one point, Open Hub analyzed source code for this project based on code location(s) available at that time. Since then, the code locations have been removed.