Design the HLD and LLD diagram.

When asked to design the HLD (High‑Level Design) and LLD (Low‑Level Design) diagram, start by identifying the major components and their responsibilities. In the HLD, sketch the system’s architecture: user interface, API gateway, business logic layer, data layer, external services, and deployment topology. Show how components communicate (REST, gRPC, message queues) and highlight scalability, fault tolerance, and security considerations. Next, move to the LLD, where you detail each component’s internal structure. For the business logic layer, list classes, interfaces, and data models; for the data layer, outline tables, relationships, and indexing strategies. Include sequence diagrams or flowcharts to illustrate interactions for key use cases. Keep the LLD focused on implementation details that a developer would need to code, such as method signatures, error handling, and configuration. By separating concerns, the HLD provides a blueprint for stakeholders, while the LLD gives developers a concrete plan to implement.