As far as i know there is no way to query or a document that tells you what marketplace modules you use in your project. The only way i know how to easily find this is when you go to your app explorer and then under app, which is the top one in your explorer, there is an item called marketplace modules and under there you find all the modules that come from the marketplace.
Hope this helps in a way.
Do You mean open the project directory in windows explorer? In can find only some marketplaces stuff in the widegt folder. But it isn’t a complete overview.
Thanks and regards
Per module, you can only query data from a project using the Mendix Model SDK or the bundled MPR tool, found inside Mendix bin directory.
Visually, from Mendix Studio / Pro you can only check for widgets.
Widgets: App → Tools → Check Widgets
Hope this helps