The article describes the results of the first year of the Centre Mersenne for Open Scientific Publishing, a diamond open access platform for scientific publications developed by Mathdoc, a joint service unit based in Grenoble (France). The Centre Mersenne was launched on 1st January 2018 to offer the scientific community a new open access publication solution for journals publishing in LaTeX and thus contributes to bibliodiversity. This article discusses challenges faced by the Centre Mersenne while implementing concretely its goals, refining its business model, and actions taken to address the needs of new journals. This article specifically focuses on the three new journals launched during that year, among which two newly-created and one ‘flipped’ journal, as well as two newly-migrated journals from Cedram, a dissemination platform for mathematics journals bound to disappear.