mixmello - mixmello is a free, open source tool to create remixed versions of your favourite playlists.
Visual Beat - Interactive music video
remixmonsta - Tired of Despacito? Find a cool remix instead
Splice Beat Maker - Make and share beats in your browser
The Rick Astley Remixer - Remix your favourite songs in your browser.
Sampulator - Make (and record) beats on your keyboard