This study investigates conflict markers that occur during online communication in business families. Our findings identified eleven different markers that point to escalating conflict. We not only confirmed the applicability of Gottman’s conflict markers (1994) to the business family realm, we also identified unique markers in the realm of digital communication as well as specific markers in the context of business families. Implications and future research directions are discussed. • We find 11 conflict markers in online conflict escalation in family firms. • We show the presence of the four horsemen of the apocalypse (criticism, defensiveness, contempt, stonewalling). • We show digital conflict markers (punctuation, greetings/signoff, expansion of the recipient group and direct quotes). • We show family firm specific conflict markers (monetary hyperboles, separation as well as mixing of private and business).