Play music anywhere on this computer, then share its audio here. The visuals react to what you hear, live.
How to share audio
Windows (Chrome or Edge): pick Entire screen and turn on Also share system audio. Spotify's desktop app works.
Mac (Chrome): open the Spotify Web Player in another Chrome tab, pick that tab, and keep Also share tab audio on. Newer macOS and Chrome versions also offer system audio on Entire screen.
Safari or Firefox: these can't share sound, so choose Use audio input. A microphone works, or install a loopback driver such as BlackHole, route your Mac's output to it (Audio MIDI Setup → Multi-Output Device, so you still hear the music), and pick it from the input list.
The video part of the share is ignored. Only the sound is analysed, and nothing leaves your machine.