This study scrutinizes the nature of online citizen-driven collective actions aimed at countering terrorism following bombing attacks in Indonesia. In particular, this study illuminates the framing processes, public sentiments, and actors involved in the movement. An analysis of 10,000 tweets bearing the hashtag #KamiTidakTakut (we are not afraid) showed that the participants predominantly employed motivational frames to encourage others to engage in anti-terrorism efforts and defy terror by bolstering collective identity. Moreover, while the tweets were mainly conveyed in a positive tone, a considerable number of tweets voiced negative sentiments, including criticism of the movement. In addition, most tweets came from citizens, and some were from media outlets, civil society organizations, government agencies, and public figures. The study enriches the literature on online collective actions in the context of terrorism and offers practical insights into the design of public anti-terrorism campaigns.