Neptunely: https://neptunely.com

I've been building a procedural music generation engine for the last 2 years. It's been a passion project. There are a handful of videos on youtube that showcase it. It can generate pretty good songs and transitions based on established rules. I'm hoping to make it more generally accessible soon, but so far I've just been using it to help me make my music: https://open.spotify.com/artist/3Xtq9IlfA0l3dNPe3lhGAY