AudioVis

AudioVis - Free Real-Time Audio Visualizer, Website/Desktop App

free browser-based audio visualizer!
Drop any music file (MP3, WAV, etc.) and watch smooth reactive visuals:

Beat-reactive spectrum analyzers & waveforms
Dynamic pulsing backgrounds
Screen shake & flash effects
Multiple visual styles & custom color presets
Save your own presets

Completely free, no sign-up, no watermarks. Works great on desktop and there's also a downloadable desktop app.
Whether you're a music producer, DJ, streamer, or just love listening to music with visuals, give it a try!