Startup.Auth.cs

public void ConfigureAuth(IAppBuilder app)
{
    //other stuff
    app.Use(async (context, next) =>
    {
        IOwinRequest req = context.Request;
        IOwinResponse res = context.Response;
        if (req.Path.StartsWithSegments(new PathString("/Token")))
        {
            var origin = req.Headers.Get("Origin");
            if (!string.IsNullOrEmpty(origin))
            {
                res.Headers.Set("Access-Control-Allow-Origin", origin);
            }
            if (req.Method == "OPTIONS")
            {
                res.StatusCode = 200;
                res.Headers.AppendCommaSeparatedValues("Access-Control-Allow-Methods", "GET", "POST");
                res.Headers.AppendCommaSeparatedValues("Access-Control-Allow-Headers", "authorization", "content-type");
                return;
            }
        }
        await next();
    });
    //other stuff
}