When creating a Soundiiz account, you can use directly your email and create a password but you can also a social profile or directly use a music account.
Be aware when creating a Soundiiz account using "Sign in with Spotify" or any other music service, we will directly requiring more scope/access then necessary for the login. However, that allowing us to directly connect your music account to Soundiiz and displaying immediately your playlists, albums etc.
Soundiiz is not only a tool to transfer your playlists between music services, but also a music account manager, allowing us to delete elements, update playlists, retrieve your favorites etc...
API scopes required by Soundiiz is large due to all operation Soundiiz can support.