Before reading this post, you must be aware of basics of identity server and oauth terms. We will not delve into the basics of identity server here. Setting up identity server 4 Setup a .Net Core 3.x project and add the nuget package reference for Identity server 4. Important point here is to have a project with a flexibility to add new views/pages. Once we add the nuget reference of Identity server 4, we will add a few lines of code in ConfigureServices method of our Startup.cs file Here is a look at our Config.cs class This way we have added a client with a custom grant type "iwa" representing integrated window authentication. This will be used in part 2 when we will protect our API resources for a SPA. Window authentication with hybrid flow i.e. MVC client Next we will create a MVC project (you can create any web project). We need to ensure that the client parameters used in this project should be same as registered in Identity Server setup. Here is t