Approval systems for restricted antimicrobials are listed as an essential strategy in the Australian Commission on Safety and Quality in Healthcare [1] AMS Clinical Care Standard. The Open-Source Antimicrobial Stewardship Project (OSAMS) is a collaborative project to develop a free and open-source system to provide restricted antimicrobial approval and prescription advice. This system differs from most traditional/commercial antimicrobial approval systems. Rather than assuming prescribers have prior knowledge of which antimicrobial is best for their patient, instead it provides a clinical decision support pathway for each approval code, helping to guide prescribing to achieve best outcomes.