Sample for how to use appsettings.json + overrides to populate web.config/app.config AppSettings and ConnectionStrings

This sample application shows how to use configuration builders (introduced in .NET 4.7.1) and the configuration system introduced in ASP.NET Core (Microsoft.Extensions.Configuration) to load appsettings.json files and overriding per-environment files like appsettings.Development.json to populate app settings and connection strings usually set in web.config (also works for console apps and App.config).