Crowdify is a web app that generates playlists for Spotify. An organiser can create an event, which attendees can then click to attend by clicking a URL. We then aggregate the music preferences of all the attendees, and generate a playlist which matches the preferences of the attendees as closely as possible. When the organiser clicks the button on the event page, this playlist is generated in their spotify account.
Whether at parties, conferences, or meetings, we often need to generate music that a large group of people will like. We'd prefer to be able to do this without explicitly requiring the user to specify songs (as we can do in a collaborative playlist, for instance), instead automatically fetching the user's song preferences which already exist in their Spotify account.
We don't store any personally identifying information from guests who add their preferences to a playlist. We only store a list of the 50 top songs from each (anonymised) user.