Integrating third-party vendors' APIs is described. A system identifies a current call from a client computing system to an API associated with a third-party vendor, the current call including a configuration file for calling the API. The system determines whether a previous call was made to the API. The system determines whether part of the configuration file in the current call matches a corresponding part of a configuration file in the previous call, in response to a determination that a previous call was made to the API. The system uses a previously parsed configuration set, associated with the part of the configuration file in the current call, to configure a request in the current call and/or a response to the current call, in response to a determination that the configuration file in the current call matches the configuration file in the previous call.