A gRPC developer designs, builds, and maintains highly scalable and efficient service-to-service communication using Google's high-performance, open-source universal RPC framework, gRPC. They create ProtoBuf services and messages, ensuring seamless serialization and deserialization of data. They handle network protocols, manage server-side and client-side streaming, and implement error-handling and load balancing. They also integrate gRPC with other technologies and create APIs. Their work is crucial for microservices architectures, enabling efficient, low-latency communication between internal services. They also ensure the security of data transmission by implementing authentication and encryption methods.