Very likely EchoNest. Used in rdio as well.<p>And while these algorithms work up to a degree at some point it&#x27;s not useful anymore - especially if your taste is very specific and not dependent on obvious factors like genre or mood (I know, Echonest takes a lot more properties into account).<p>These days I see what feels like the same recommendations everywhere. Rdio solved this problem with good old fashioned human curation - and in contrast to Apple Music it&#x27;s based on humans I want to follow, not some show host or editor that has to appeal to large crowds.