SoapUI is a tool which can be used for both functional and non-functional testing. It is not limited to web services, though it is the de-facto tool used in web services testing.
Following are some important features of SoapUI.
It is capable of performing the role of both client and service.
It enables the users to create functional and non-functional tests quickly and in an efficient manner using a single environment.
It is licensed under the terms of the GNU Leaser General Public Licence (LGPL).
It is purely implemented using JAVA platform.
It supports Windows, Mac, multiple Linux dialects.
It allows testers to execute automated functional, regression, compliance, and load tests on different Web API.
It supports all the standard protocols and technologies to test all kinds of APIs.
SoapUI can be used to test complete RESTful API and SOAP Web Service testing. It supports Functional Testing, Performance Testing, Interoperability Testing, Regression Testing, Load Testing, and much more.
It is user friendly as well as it is easy to convert functional test into non-functional tests such as Load, Stress testing.