We introduce ExtremeBB, a textual database of over 53.5M posts made by 38.5k users on 12 extremist bulletin board forums promoting online hate, harassment, the manosphere and other forms of extremism. It enables large-scale analyses of qualitative and quantitative historical trends going back two decades: measuring hate speech and toxicity; tracing the evolution of different strands of extremist ideology; tracking the relationships between online subcultures, extremist behaviours, and real-world violence; and monitoring extremist communities in near real time. This can shed light not only on the spread of problematic ideologies but also the effectiveness of interventions. ExtremeBB comes with a robust ethical data-sharing regime that allows us to share data with academics worldwide. Since 2020, access has been granted to 49 licensees in 16 research groups from 12 institutions.
@article{arxiv.2111.04479,
title = {ExtremeBB: A Database for Large-Scale Research into Online Hate, Harassment, the Manosphere and Extremism},
author = {Anh V. Vu and Lydia Wilson and Yi Ting Chua and Ilia Shumailov and Ross Anderson},
journal= {arXiv preprint arXiv:2111.04479},
year = {2025}
}