pntOS is an open source, government-owned plugin architecture for building integrated PNT sensor fusion applications for all operational environments. Designed for cost, schedule, and performance efficiencies, pntOS features standard message formats that make all plugins - GOTS, community shared, and proprietary - individually swappable without the need for modification. Custom plugins can be developed using any programming language and made available to the pntOS community or used for proprietary applications without risk of disclosure.