This is .Net application (with desktop and mobile UI) written in C# programming language.

.NET is a free, cross-platform, open source developer platform for building many different types of applications.

Application consists of services for work with data implemented through APIs(REST) and UI(Desktop and mobile).

Desktop UI will be used by workers of car rental agency and mobile UI will be used by clients.

Database : SQL Server

WEB API : .NET Core 2.1 (Flurl used for as HTTP client library)

Desktop Authentication: Basic Authentication

Mobile Authentication: Basic Authentication

Desktop UI: Windows forms with (Metro UI) --> https://thielj.github.io/MetroFramework/

Mobile UI: Xamarin --> https://visualstudio.microsoft.com/xamarin/

Xamarin provides a developer with tools that can help them in building cross-platform mobile applications.

At the very root level, Xamarin has converted the entire existing Android and iOS SDK to C# so that you can code in a more familiar language.

Flurl is a modern, fluent, asynchronous, testable, portable, buzzword-laden URL builder and HTTP client library.

Flurl is available on NuGet and is free for commercial use. It runs on a wide variety of platforms, including .NET Framework, .NET Core, Xamarin, and UWP.

Official site --> https://flurl.dev/

Github --> https://github.com/tmenier/Flurl