Abstract Most flaming research addresses explanations for and the immediate effects of flaming on those engaging in and targeted by flaming. However, online interactions are increasingly visible, suggesting that understanding third-party evaluations of flaming is important. By integrating considerations in computer-mediated communication theorizing with the social-perceptual effects of online moral outrage, we explore how third-party observers evaluate flaming, also assessing beliefs about the signaling social function that flaming serves. In seven experiments (total N = 3,178), we manipulated the intentionality of triggering events and compared flaming to other types of online responses (less-toxic criticism; supportive), measuring reactions including moral regard, comment approval, and positive/negative engagement. Findings suggest that flaming may sometimes act as exculpable moral outrage when responding to egregious behaviors. However, contrary to participants’ beliefs, flaming does not reliably or persuasively influence perceptions of those whom it targets; rather, it mostly appears to send negative signals about the flamer.