Domain-driven designs are often employed by organizations with complex domain models, typically implemented through REST-based architectures for API entry points. While REST APIs are easy to use for single-domain data, developers face challenges when they need to aggregate data across multiple domains for various applications, often leading to the creation of maintenance-heavy "back-end for front-end" APIs. GraphQL addresses these challenges by allowing flexible queries and decoupling clients from domain services, as exemplified in the fictional airline KongAir's system. KongAir uses GraphQL to aggregate its existing REST APIs, providing a dynamic API experience for developers building user-facing applications. This approach is built on the Apollo Server, where a single GraphQL query can combine data from multiple REST APIs, making it easier for developers to tailor data retrieval to specific application needs without creating new backend services. The process involves defining a GraphQL schema, setting up data sources, and configuring resolvers to map queries to data sources, enabling seamless integration across different domains and simplifying data access for client applications.