Integrating payment gateways into distributed microservices requires decoupled communication models and strict protocol separation. This technical guide explains how to implement PayPal in a microservices architecture using NestJS, gRPC, and Docker. Learn Proto contracts, run dual HTTP and gRPC transport layers in a single process, handle PayPal v2 checkout orders, and orchestrate containerized services. #NestJS #gRPC #Microservices #Docker #PayPal #Backend #Nodejs #APIs #SoftwareArchitecture