We can also use apps that can compose and send HTTP requests from mobile devices to work with our RESTful Web Services. For example, we can work with the iCurlHTTP app on iOS devices such as iPad and iPhone: https://itunes.apple.com/us/app/icurlhttp/id611943891. On Android devices, we can work with the HTTP Request app: https://play.google.com/store/apps/details?id=air.http.request&hl=en.

The following screenshot shows the UI for the iCurlHTTP app running on an iPad Pro:

At the time of writing, the mobile apps that allow you to compose and send HTTP requests do not provide all the features you can find in Postman or command-line utilities.