oRPC is an API toolkit that combines the familiarity of Remote Procedure Call (RPC) with the industry-standard OpenAPI spec, enabling type-safe APIs from client to server. It addresses common issues such as schema drift and integration bugs by collapsing definition, implementation, and documentation into a single, type-safe contract that travels unchanged throughout the system. This approach ensures end-to-end type-safety, contract-first design, and zero code-generation, making it suitable for micro-frontends, BFFs, edge-first workloads, and teams that care about OpenAPI. oRPC provides a flexible architecture for handling errors, including two approaches to error definitions using `.errors()` and fully typed error definitions using `ORPCError`. It also supports authentication and protected routes with the use of context objects and JWT parsing. By using oRPC, developers can write functions and get fully typed, OpenAPI-compliant endpoints without code-generation or drift, resulting in a single source of truth for their APIs.