Soundz is a Music Player built by me with ReactJS which was integrated with the Spotify API so as to get a user's required data of tracks to be played. Hence, a user needs to have a Spotify account before one can make use of the features of the App. So, you can go ahead to create an account and create your playlist if you do not have one yet.
The mobile screen is still under design at the moment, likewise with more features. Though for now, a connected user can play snippets (access to a 30 seconds snippets of tracks is given by Spotify) of tracks in an existing playlist.