JM Berger offers a fascinating comparative analysis of Nazi and ISIS uses of twitter. Shocking white supremacists have outpaced ISIS in using social media. Published by GWU’s Program on Extremism 

Please check out his excellent book written with Jessica Stern: ISIS: The State of Terror 

Abstract from his intewire webiste

“The Islamic State, also known as ISIS, has distinguished itself as a pioneer in the use of social media for recruitment. But, while ISIS continues to be one of the most influential terrorist groups in the material world, other extremists are closing the gap in the virtual realm. On Twitter, ISIS’s preferred social platform, American white nationalist movements have seen their followers grow by more than 600% since 2012. Today, they outperform ISIS in nearly every social metric, from follower counts to tweets per day. This study examines and compares the use of Twitter by white nationalists, Nazi sympathizers, and ISIS supporters respectively, providing some preliminary comparisons of how each movement uses the platform.”