Ember.js was developed by Yehuda Katz and initially released on in December 2011.
The correct answer to the question “Who was the author of Ember.js?” is Yehuda Katz. He co-created Ember.js along with Tom Dale, Alex Matchneer, and Evan Phoenix. Yehuda Katz is a well-known figure in the JavaScript community and has contributed significantly to various open-source projects and web development frameworks.