This website is a visualizer. It includes rapidly flashing red lights. It is extremely dangerous for those prone to photosensitive seizures.
Please do not use this if you are prone to photosensitive seizures.
To use it, open an audio source (like YouTube or Spotify web player) in another tab in Chrome, then come back to this tab and press the 'Choose tab' button. You'll see a pop up like the below.
Press Chrome Tab, then select the tab you want to visualize, then make sure "Share tab audio" is selected. Then press Share. You tab will flip to the one you're sharing with this page. Come back to this page's tab, and your visualizer will be running.