gRPC

An open source remote procedure call (RPC) system that uses HTTP/2 for transport that provides features such as authentication, bidirectional streaming and flow control, blocking or nonblocking bindings, and cancellation and timeouts. It generates cross-platform client and server bindings for many languages. Common use cases include connecting services in microservices style architecture and connecting mobile devices and browser clients to backend services. (In English, this means that gRPC is a type of API -- and yes, we can see it and provide insight into it.)