Backend API Design for Mobile Clients Questions

Designing backend application programming interfaces specifically for mobile clients, addressing mobile device constraints, network variability, and cross platform compatibility. Core concerns include bandwidth optimization techniques such as pagination, selective field queries, delta responses, efficient serialization formats, and compression; response shape and protocol trade offs including representational state transfer versus GraphQL; versioning and backward compatibility strategies for long lived mobile applications; error handling, retry semantics, and user friendly error surfaces appropriate for intermittent connectivity; rate limiting, throttling, and quota management; real time synchronization patterns including polling, web sockets, and server sent events; caching, offline support, data synchronization, conflict resolution, and optimistic updates; authentication and token refresh strategies, security and privacy considerations; and monitoring, telemetry, testing, and deployment practices that minimize breaking changes for mobile clients.