Abstract: Analysis of an Internet content publisher's web pages to identify third-party vendor tags, as well as piggyback vendor tags called during execution of a given web page, that ultimately cause various types of secondary (“foreign”) content (e.g., ads, trackers, analytics, widgets, privacy assets) to be present in the content publisher's web pages when rendered by a browser on a client computing device. Such analysis also reveals the sources of the tags and the foreign content, and parent-child relationships (“parentage”) amongst vendor tags. A graphical representation is then rendered that includes one or more visualizations of the identified vendor tags, and the corresponding sources of the tags and the foreign content in the content publisher's web pages, as well as other information relating to the tags, the foreign content and their sources (e.g., parentage, classification of content, timing of called tags, latency resulting from tags, secure/unsecure calls to foreign resources, etc.).