SIREN.io - Siren is an investigative intelligence platform.
Linkurious - Search and visualize your graph data through a simple web-based interface
DataWalk - DataWalk is a software platform to connect numerous large data sets, both external and internal, into a single repository for fast visual analysis.
Gephi - Gephi is an open-source software for visualizing and analyzing large networks graphs.
SpiderFoot - Open source intelligence (OSINT) automation tool.
Maltego - Maltego is an open source intelligence and forensics application.