What are some alternatives?
When comparing HearSeeParty and ImageGlitcher.com, you can also consider the following products
Glitchatron - Destroy your favorite photos
Photomosh - Turn anything into a vaporwave
MVGEN - Make your own music videos with audio, gifs, and special effects
Tumblr Music Video Generator - turn Tumblr accounts into music videos
Decim8 - Turn photographs into glitch art
VOCHI Video Effects - Mobile video editor that lets you apply video effects to single objects.