Underground forums are valuable for understanding cybercrime, offering insights into economies, key actors, and various types of cybercriminal activities. While historical challenges included limited access to data, recent developments have provided vast datasets of forum messages. However, analyzing these large datasets remains difficult for non-technical users due to the complexity of available tools. To address this, Postcog has been developed—a web application designed to facilitate data exploration and analysis for both technical and non-technical users. Postcog supports functionalities like search, information extraction, and cross-forum comparison. The tool’s usability was evaluated through user studies with experts from the Crimebb dataset and is available for academic research through the Cambridge Cybercrime Centre.