Resources that fulfill fundamental needs must have a participatory governance, regardless of who owns them (Rodotà Commission and Italian Supreme Court building on Nobel Prize Dr Elinor Ostrom). Examples: open-source hand rub saves 8 million lives yearly; open-source MRI scanners could spare 60-140 million € yearly in Germany alone; open-source prostheses mobilize 30000 volunteers with a 0 € business model; Open Source Drug Discovery gathers 110 projects on neglected diseases; open-source games for health showcase a ludic model to mutually take care. It is vital because: 1) being healthy requires commoning: 2) it can double access to care; 3) it helps fight corruption; 4) costs can be cut by 10 or 100. Additional resources: reminder of definitions (free/libre and open-source vs gratis); three steps to start (Goals, design principles, validation); self-assessment (health, people, process, licences, resource allocation, physical availability, impact); links to guide for makers, poster with further examples, report on open source in Switzerland.