Reign for Spofity allowed you to control a local Spotify instance from any device on the same local network. It was a free app and the source code is available on GitHub.

The Spotify remote for friends, colleagues, housemates and yourself that works in any browser.

Controlling Spotify from a browser through Reign

Do you use Spotify? Try these:

Denied app icon

Denied

Skips terrible music

Denied saves your ears from Nickelback or any other band, song or album. It sees what you're playing and automatically skips songs that you dislike.

macOS Audio Spotify iTunes Apple Music

Relax app icon

Relax

Mutes internal speakers

Relax automatically mutes your internal speakers and pauses music apps when you disconnect headphones.

macOS Audio Spotify iTunes Apple Music