The University Library at OsloMet started running the OJS platform for publishing open access journals in 2011. The platform quickly grew from three start-up journals, to today's 15 published journals. The free service expanded from focusing on running a platform, to offering support on all levels of academic journal publishing. They provide advice on peer review, DOis, indexing, publication formats, financing and facilitate experience sharing between journals. At a cost, they also publish journals for other institutions in Norway, and regularly receive requests to include more journals. This presentation shares experiences from building a publishing platform, lessons learned along the way, and goals for the future of sustainable library publishing