At a time when scientific findings are still too often hidden behind paywalls, Berlin Universities Publishing (BerlinUP) is sending a clear message of openness. Founded by Freie Universität, Humboldt University, the Technical University, and Charité – Universitätsmedizin Berlin, this open-access publisher makes research findings freely available worldwide—at no cost to authors or readers. Instead of relying on costly publication fees, BerlinUP is committed to the principle of Diamond Open Access and institutional funding. In this interview, Jürgen Christof, the current spokesperson for the publisher and director of the University Library at TU Berlin, explains how BerlinUP aims to make access to knowledge more equitable and why the four partner institutions are working together on this initiative.