I can imagine that it is really hard to maintain the codebase or at least keep the dependencies up to date. How many devs are working on this project?

I loved 8tracks. Got several friends to use it. But about 6 months back the Android app update screwed up the whole experience. Skipping songs, loading problems, sign in not working - I waited for several weeks but the experience was still awful and I had to stop using the app. I think I will try using it again though, because the content is just amazing.

It's nice to see a sentence or two on the practical applications, instead of just a list.

More about their recommendation engine stack: https://www.dominodatalab.com/casestudy/casestudy_8tracks

I clicked around and suddenly had multiple tracks playing. No way to stop them all anymore, other than closing the tab.