In this study, we select the official websites of four known extremist groups and map the networks of hyperlinked websites forming a virtual community around them. The networks are constructed using a custom-built webcrawler (TENE: Terrorism and Extremism Network Extractor) that searches the HTML of a website for all the hyperlinks inserted directing to other websites (Bouchard et al., 2014). Following all of these hyperlinks out of the initial website of interest produces the network of websites forming a community that is more or less cohesive, more or less extensive, and more or less devoted to the same cause (Bouchard and Westlake, 2016; Westlake and Bouchard, 2016). The extent to which the official website of a group contains many hyperlinks towards external websites may be an indicator of a more active community, and it may be indicative of a more active social movement.