A developer who loves digging in apps' code to find hidden or still unreleased features tweeted about a pretty cool Spotify functionality called "Social Listening", which lets you and your friends listen to the same song at the same time.
Spotify is working on Social Listening, letting friends to control music together with their own devices— Jane Manchun Wong (@wongmjane) May 31, 2019
Scan Spotify Code or open link for it to begin
For example, I'm listening Spotify right now. Feel free to introduce me new music: https://t.co/f59D0sis7Y pic.twitter.com/nPOlcPwQdG
Moreover, everyone in the party can contribute to the playlist by adding tracks of their own. All you have to do is scan a Spotify Code or open the link to the social playlist. The "Now Playing UI" will show the number of friends connected to the playlist.
However, the feature is still in its testing period so it might take some time for Spotify to release it to the wider public.
And features like these is why I pay for Spotify premium