WSDL and OpenAPI/Swagger solve similar problems. Roughly speaking: WSDL is to XML web services as OpenAPI is to REST They both model the API and message struc

WSDL and OpenAPI/Swagger solve similar problems. Roughly speaking: WSDL is to XML web services as OpenAPI is to REST They both model the API and message structure of an API. AFAICT WSDL goes a little farther in that you can declare message sequences (I might be giving short shrift to OpenAPI here).