Postman is a great tool to showcase how APIs work. The collections for commercetools are very sophisticated and provide all the details you need in order to demo their capabilities.
However, sometimes it is just great to know alternative ways to demo certain aspects. Especially from a developer perspective, Visual Studio Code seems to be the de-facto standard nowadays. VS Code has a huge ecosystem of extensions available … and one of these is REST Client created by Huachao Mao.