Startup.cs

using NonCreative.AuthSystem;
using Microsoft.Owin;
using Microsoft.Owin.Security.OAuth;
using Owin;
using System;
using System.Web.Http;

[assembly: OwinStartupAttribute(typeof(NonCreative.Startup))]
namespace NonCreative
{
    public partial class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            HttpConfiguration config = new HttpConfiguration(); 

            config.Routes.MapHttpRoute("API Default NoAction", "api/{controller}/{id}",
             new { id = RouteParameter.Optional });
            config.Routes.MapHttpRoute("API Default", "api/{controller}/{action}/{id}",
            new { id = RouteParameter.Optional });

            ConfigureOAuth(app);

            WebApiConfig.Register(config);
            app.UseCors(Microsoft.Owin.Cors.CorsOptions.AllowAll);
        }

        public void ConfigureOAuth(IAppBuilder app)
        {
            OAuthAuthorizationServerOptions OAuthServerOptions = new OAuthAuthorizationServerOptions()
            {
                AllowInsecureHttp = true,
                TokenEndpointPath = new PathString("/token"),
                AccessTokenExpireTimeSpan = TimeSpan.FromDays(10),
                Provider = new SimpleAuthorizationServerProvider()
            };

            // Token Generation
            app.UseOAuthAuthorizationServer(OAuthServerOptions);
            app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions());

        }
    }
}