Spotify's new playlist tool allows you to adjust multiple parameters, or match tempo and key, to blend tracks smoothly.

You've already got the perfect playlist, now Spotify lets you add and customize transitions between songs. On Tuesday, Spotify launched a beta version for Premium users to add song transitions. There's now a mix button in the playlist toolbar that lets you mix songs for a seamless transition.

The new options are designed to appeal to playlist experts and other music fans, who have collectively created nearly 9 billion playlists on Spotify's platform to date.