I find this local HTTP server is useful for quick researches. For example, I used this server to witness a bug in Katalon Studio’s RequestObject class.
In this Katalon User Form, many people report problems about WebService tests. However, quite often it is difficult to reproduce problems without a RESTful/SOAP server counterpart up and running. This local HTTP server makes it easy to mimic the problem with test fixtures (JSON, XML files) manually prepared in the project directory locally.