TypeScript Can't Save You: The Hidden Risk of Unvalidated API Responses

TypeScript's type system provides compile-time safety but cannot validate data arriving from external APIs at runtime—a critical gap that often remains hidden until production failures occur. When third-party APIs change their response structures, type assertions silently fail despite strict type checking, leaving applications defenseless against runtime errors. This article explains why type assertions alone offer false security and demonstrates how runtime validation and schema checking provide genuine protection against API surprises.