iHRIS Retain is an open source tool to cost health worker retention interventions. People living in rural and remote areas need more skilled health workers to care for their communities. However, attracting and retaining health workers to serve in these areas is a challenge. Developed by CapacityPlus in collaboration with the World Health Organization (WHO), iHRIS Retain is based on the WHO’s 2010 global policy recommendations on retention, which offer guidance on the different interventions in the areas of education, regulation, financial incentives, and professional development that can increase access to health workers in remote and rural areas through improved retention. iHRIS Retain guides users through the costing process step by step, collecting necessary data, calculating the costs of interventions, and comparing costs to available funding. The resulting information can then be used to develop retention strategies at the district, regional, or national level.