As mobile apps scale, REST APIs become fragile: schemas drift, contracts remain weakly typed, and versioning breaks clients at runtime. GraphQL adds flexibility, but often shifts complexity to client teams through large queries, orchestration logic, and debugging challenges—problems that are amplified in mobile environments. This talk explores why REST and GraphQL start to fail mobile clients at scale, and how gRPC with Protocol Buffers provides a stronger alternative. Using a live migration of a sample app, we’ll introduce gRPC incrementally, run it alongside existing APIs, and migrate endpoints safely without breaking users. While Android is used for demonstration, the same gRPC contracts are shared across Android, iOS, Flutter, and Web, showing how a single strongly typed API can serve all platforms consistently.