Awesome

ripchord

Ripchord is a free MIDI plugin for Mac and PC that makes it easy to create, perform and remix chord progressions. The plugin manual and download can be found here: https://trackbout.com/ripchord

open source

Ripchord is open source under the GNU General Public License v3.0. The license can be found here: https://github.com/trackbout/ripchord/blob/master/LICENSE