This is like my own little tonality calculator, except with good UI/UX, and with two changes (Ionian/Aeolian) instead of arbitrary changes. What would be super cool would be to combine the best of both somehow. My change calculator is at https://edrihan.neocities.org/changedex if anyone wants to derive harmony of changes which are not Ionian/Aeolian. Though it looks like a turd from 1997, and the audio doesn't work, it does expand this idea to include all 12-tone possibilities, which I call changes. Also hit me up if you like OP!