SoapUI
SoapUI is a dedicated API testing tool with strong support for both SOAP and REST APIs, offering a graphical interface for building, executing, and automating API test cases — historically the standard tool for SOAP-based web service testing specifically.
SoapUI's particular strength is its native handling of WSDL-defined SOAP services — it can import a WSDL file and automatically generate test requests matching the service's full formal contract, a capability Postman and most REST-focused tools don't offer with the same depth for SOAP specifically.
While it also supports REST API testing, most teams working primarily with REST APIs today default to Postman for its simpler interface and broader ecosystem — SoapUI remains the more common choice specifically in enterprise and legacy environments still running SOAP-based services alongside newer REST APIs.
