An ArcGIS Runtime SDK developer creates applications that employ geospatial and mapping capabilities. They use ArcGIS software development kits (SDKs) to integrate GIS data, functions, and visualization into their applications. They work with various APIs to design interactive maps, analyze spatial data, perform route planning, and create geodatabases. They also enable offline functionality for field operations. The developer is responsible for debugging and maintaining the applications while ensuring they meet user needs and expectations. They must stay updated with GIS trends and technologies, and often collaborate with other team members to deliver robust and efficient GIS solutions.