It&#x27;s entirely custom but it leverages the d3 library so it&#x27;s quite short&#x2F;relatively simple in its execution as it leaves most of it up to d3.<p>Process for finding out is not fixed. Generally a simple &quot;View Source&quot;, look at &lt;script&gt; tags, read script files and look for obvious clues is the best first port of call (and worked easily here). If there&#x27;s a lot of indirection and pre-compilation being done it gets harder.