Music Blocks is a fork of Turtle Blocks created by Walter Bender. Turtle Blocks JS has many other contributors, you can find them from here.
Much of the initial coding of the fork from Turtle Blocks was done by Yash Khandelwal as part of Google Summer of Code (GSoC) 2015.
Additional contributions are being made by Tayba Wasim, Dinuka Tharangi Jayaweera, Prachi Agrawal, Cristina Del Puerto, and Hrishi Patel as part of GSoC 2017.
Also many students contributed to Music Blocks as part of Google Code-in (2015-16 and 2016-17).