The pervasive practice of botting by using fame-enhancing bots and operating porn bots, and Instagram’s opaque and unreliable authenticity governance, has evoked human Instagram users to actively police and govern botting and other bot activity. Botting describes repetitive and quantitative posting, messaging and engaging on social media platforms to provoke reciprocal engagement. Running bot police accounts, Instagram users engage and try to play an active role in the authenticity governance process of Instagram. The article investigates why and how Instagram users govern two types of “inauthentic” Instabots, which concentrate on detecting automated interactions by fame-enhancing bots and reporting porn bots. Two case studies of three Instagram accounts and their content show different approaches to user-led authenticity governance and how these profiles perceive themselves as custodians of “authenticity.” The key findings reveal that their activities of pillorying and collective flagging are considered digital vigilantism that potentially cause harm to other users. Furthermore, they show mechanisms of peer surveillance and mutual moderation on a user level, and complex power asymmetries between the platform company, its moderation systems, advertisers, and its users.