No alternative on repository.
Carla is an audio plugin host, with support for many audio drivers and plugin formats.
It has some nice features like automation of parameters via MIDI CC (and send output back as MIDI too) and full OSC control.
Carla currently supports LADSPA (including LRDF), DSSI, LV2, VST2/3 and AU plugin formats, plus GIG, SF2 and SFZ file support.
It uses JACK as the default and preferred audio driver but also supports native drivers like ALSA, DirectSound or CoreAudio.