Each running coach is choosing the music, and adjusting things like tempo based on what the specific workout is.

Regarding copyright, we keep track of each song played, and the number of people that listen. We then send this to the large music groups each quarter, and pay royalties.

How are you technically pulling this off? E.g Are you integrated with Spotify and leveraging an API to stream music? I love the idea by the way, just curious about the implementation.

We're streaming the audio through a server that tracks which song is played, and records each one. We actually use the same technology that powered internet radios back it the Winamp days.

On the software side, we use Djay pro, which can forward the song id along to the server for recording the data.