tRPC (TypeScript Remote Procedure Call) is a framework for building end-to-end type-safe APIs. You define server-side functions (procedures) in TypeScript, and tRPC generates a strongly-typed client for your frontend. Call server functions directly from your frontend with full autocomplete and type checking—no REST endpoints, no API documentation, no serialization gaps. tRPC is ideal for full-stack TypeScript apps (Next.js, SvelteKit, Remix). The backend and frontend share the same types, so changes propagate automatically.