Yup, code.org uses Blockly.<p>Source: I worked on the original &quot;Hour of Code&quot;.<p>Source Code: <a href="https:&#x2F;&#x2F;github.com&#x2F;code-dot-org&#x2F;code-dot-org" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;code-dot-org&#x2F;code-dot-org</a>