The whitepaper with the title “Tackling terrorist content online – Propaganda and content moderation” examines how the tech industry deals with online terrorist and violent extremist content, which is a major factor in radicalisation and violence, according to recent reports and studies. The whitepaper consists of three parts: the first part gives some background on the online platforms and methods used by terrorists and extremists; the second part outlines the industry responses, such as user and law enforcement referrals, AI detection, and cross-platform collaboration; and the third part raises some issues for discussion, such as transparency, definitional clarity, impact, and prediction. The whitepaper is relevant for the research and innovation activities of two EU funded projects, TATE and NOTIONES, which involve various stakeholders in the counterterrorism and intelligence domain.