Page Speed Insights by Google is a pretty nifty tool. You can use Highlight Critical Path which shows where your scripts are loaded – kind of like the Chrome Dev Tools Network Panel – but this tool has a nice UI where you can click to see the loading paths. And also heaps of page speed suggestions on the left.
Find Images Loaded by CSS with Google Critial Path Explorer.
Also you can Find out which JS files are loading others with Google Critial Path Explorer.