You have two problems: 1) You are asking babel to load babel ! <script type="text/babel" src="https://unpkg.com/babel/standalone@6/babel.min.js"></script> remove the attrib type="text/babel" + let the Browser do the loading from CDN 2) As others already said, your MyTag component should be loaded by babel (not by the Browser) 3) Then it will work ! And I did not just give some bullshit answer, i actually tried it .. haha !