CORS example - .NET Core

startup.cs

public void ConfigureServices(IServiceCollection services)
{
  services.AddCors(options =>
  {
    options.AddPolicy("nameOfPolicyHere", builder =>
    {
      builder.WithOrigins("array of strings", "representing origins");
      // headers can be complext to start with, so I would start with
      //builder.AllowAnyHeader();
      // just to get it working first, then reduce the number of headers
      // that you allow with something like the following
      builder.WithHeders(HeaderNames.Referer);
      // Similaraly with methods, it can be useful (fro dev sites) to
      // start out allowing everything with the following:
      // builder.AllowAnyMethod();
      // Once you have it up and running, reduce the number of methods
      // with something like
      builder.WithMethods(HttpMethods.Get, HttpMethods.Post);
    }
  }
}