//WebApiConfig.cs
            config.SuppressDefaultHostAuthentication();
            config.Filters.Add(new HostAuthenticationFilter(OAuthDefaults.AuthenticationType));

            // Маршруты Web API

            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{action}",
                defaults: new { id = RouteParameter.Optional }
            );
//Startup.cs
[assembly: Microsoft.Owin.OwinStartup(typeof(API.Startup))]

namespace API
{
    public partial class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            Logger log = new Logger();
            var config = new HttpConfiguration();

            try
            {
                AreaRegistration.RegisterAllAreas();
                WebApiConfig.Register(config);
                FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
                RouteConfig.RegisterRoutes(RouteTable.Routes);
                ContainerConfig.Config(config);
                IdentityConfig.Config(app, config);

                config.MapHttpAttributeRoutes();
                config.EnsureInitialized();

                app.UseWebApi(config);

                log.WriteInformation("Application success start");
            }
            catch
            {
                log.WriteFatal("Application fail start");
            }
        }
    }
}