Delphi with the FireMonkey framework is a great tool to quickly build REST clients. I wanted to build out a Delphi project to go along with the Christmas holiday and I came up with a project where I combined the REST Client in Delphi with the Open Movie Database REST API to display Christmas movies. There is a blog post of the whole build over on the Embarcadero Community site which explains it in detail. The FireMonkey client should run on Android, IOS, MacOSX, and Windows. Source code for the full project is up on GitHub for free. In the project there are some good concepts explored like: downloading an image from a URL and displaying it, using FireMonkey premium styles to theme out the app, dynamically displaying image content and paging through it, dynamically configuring the display of content based on the device, deploying the TTabControl as a view controller, using TFrame to visually build out a re-usable component, utilizing the low code LiveBindings to display a lot of content quickly, and automatically importing JSON from the REST API to a TFDMemTable. You should be able to use these same concepts in C++Builder as well. If you are looking to consume your own REST API with Delphi be sure to read the full blog post and check out the source as there are some nice pointers in there on what worked for me.
Head over and check out the full blog post about building out a REST Client with Delphi FireMonkey.