<p>Microaggressions are subtle yet pervasive forms of prejudice that reinforce exclusion and marginalisation within social spheres. The theory of microaggressions has been widely applied to concepts of racial discrimination, while a few have applied such theory to other characteristics, like sexual orientation, and even fewer have examined concepts of within-group microaggressions, such as femmephobia or sizeism. This study examines within-group microaggressions among Grindr users, particularly focusing on femmephobia and sizeism as two of the most significant issues in relevant literature, by using a harm-oriented framework informed by theories of oppression and microaggressions. Drawing on survey responses and qualitative narratives (N = 100), three interconnected themes emerged: degradation, exclusion, and monitoring and conformity. Findings indicate that microaggressions on Grindr operate as mechanisms of discipline and punishment, while they can have significant effects on users. By shifting the focus from individual actions to collective harm, this research contributes to a harm-oriented understanding of microaggressions, arguing that they function as tools of control that sustain exclusionary norms and social hierarchies within online dating platforms.</p>