Config.cs

using IdentityServer4;
using IdentityServer4.Models;
using System.Collections.Generic;
using System.Security.Claims;

namespace askitoniauthentication
{
    public class Config
    {
        // scopes define the resources in your system
        public static IEnumerable<IdentityResource> GetIdentityResources()
        {
            return new List<IdentityResource>
            {
                new IdentityResources.OpenId(),
                new IdentityResources.Profile(),
            };
        }

        public static IEnumerable<ApiResource> GetApiResources()
        {
            return new List<ApiResource>
            {
                new ApiResource("api1", "My API")
            };
        }

        // clients want to access resources (aka scopes)
        public static IEnumerable<Client> GetClients()
        {
            // client credentials client
            return new List<Client>
            {
                new Client
                {
                    ClientId = "client",
                    AllowedGrantTypes = GrantTypes.ClientCredentials,

                    ClientSecrets = 
                    {
                        new Secret("secret".Sha256())
                    },
                    AllowedScopes = { "api1" }
                },

                // resource owner password grant client
                new Client
                {
                    ClientId = "ro.client",
                    AllowedGrantTypes = GrantTypes.ResourceOwnerPassword,

                    ClientSecrets = 
                    {
                        new Secret("secret".Sha256())
                    },
                    AllowedScopes = { "api1" }
                },

                // JavaScript Client
                new Client
                {
                    ClientId = "js",
                    ClientName = "JavaScript Client",
                    AllowedGrantTypes = GrantTypes.Implicit,
                    AllowAccessTokensViaBrowser = true,
                    RequireConsent = false,

                    RedirectUris =           { "http://localhost:5003/callback.html" },
                    PostLogoutRedirectUris = { "http://localhost:5003/index.html" },
                    AllowedCorsOrigins =     { "http://localhost:5003" },

                    AllowedScopes =
                    {
                        IdentityServerConstants.StandardScopes.OpenId,
                        IdentityServerConstants.StandardScopes.Profile,
                        "api1"
                    }
                }
            };
        }
    }
}