SoapUI Overview
SoapUI is a free, open-source tool for testing APIs, particularly well known for SOAP web services as well as REST. It lets you create functional tests, send requests and inspect responses, build test suites and assertions to validate API behavior, and perform load and security testing of services. It can generate test scaffolding from service definitions (such as WSDL for SOAP), supports data-driven testing, and is widely used by QA engineers and developers to verify that APIs work correctly. A commercial version (ReadyAPI) adds advanced features. It is a long-established tool in the API-testing space. The full offline installer bundles the application and installs without an internet connection. It also supports mock services for simulating APIs before they exist, and Groovy scripting for advanced test logic. This page links to the official SoapUI download.