https://stochas.org/stochas/
Stochas is at it’s core a step sequencer, which means it generates MIDI notes. As such it does not generate any sound of it’s own but can be used to sequence other plugins and/or hardware synthesizers. Although it can be used for basic step sequencing, it’s main function is to provide randomness to the step sequencing process. Stochas is a previously commercial software that is now open source.