Between the GUI and the database is a CakePHP application with a RESTfull-like API
This means that any action the GUI does, e.g. adding a Permanent User, can be done by simply doing the API call that the GUI will be doing to complete the said action.
Preparing the environment
This page will detail how to get Insomnia up and running in order to interact with the API of RADIUSdesk.
This is a description of what Insomnia is Insomnia is a free cross-platform desktop application that takes the pain out of interacting with and designing HTTP-based APIs. (https://insomnia.rest/)
We assume you have already installed Insomnia and ready to follow the instructions here in order to prepare the environment.