Question: what are api testing tools?
Answer: Katalon Studio. Katalon Studio is a free test automation tool for API, Web, Desktop App and Mobile applications. ... 
SoapUI. SoapUI is a headless functional testing tool dedicated to API testing, allowing users to test REST and SOAP APIs and Web Services easily. ... 
Postman. ... 
Tricentis Tosca. ... 
Apigee. ... 
JMeter. ... 
Rest-Assured. ... 
Assertible.