An application specific interface (API) for a service that is accessible by remote procedure calls is generated at run-time from an interface language definitions file. In operation, a client application requests a connection to a server and then a runtime API generator connects to the server and downloads an interface definition language (IDL) file that defines services provided by the server. The runtime API generator parses the IDL file and generates the corresponding service API. Subsequently, upon receiving a client application request, the API generator generates a set of instructions that, when executed, emit one or more remote procedure calls that cause the server to implement the client application request. Because the API is generated at run-time, the runtime API generator enables client applications that are implemented in dynamically typed languages to access the service by providing access to the data type metadata that cannot be expressed in such languages.