Bongo Cat: https://bongo.cat/
Chrome Music Lab: https://musiclab.chromeexperiments.com/Experiments
Google Creatability Keyboard: https://creatability.withgoogle.com/keyboard/
Virtual Teremin: https://femurdesign.com/theremin/
AQWERTYON: https://apps.musedlab.org/aqwertyon/?video=R7iNSUoQ4Lk&sound=rock_organ&
Incredibox: https://www.incredibox.com/demo/