There’s a lot that you can do, to make your site more easy to discover by search-engines. One method is normalizing your URI’s, which can be done in different ways. There’s also a difference between ASP.NET Web Forms and MVC, in the way URI’s are handled and expressed.

As you probably know, Google and other search-engines punish duplicate content – and a single '/' is enough to confuse even Google. Therefore I follow some simple rules.

I’ve create a SEO-friendly HTTP module, that helps me do the following:

• If the request-URI ends with ‘/’ then remove this from the request (for web forms, this should be the other way around)
• Lowercase all URI’s
• Check for default routing (‘/index’) – if this is the request, remove '/index' from the uri (for ASP.NET Web forms, this should be, if URI ends with ‘/’, then append ‘default.aspx’.
• Check for www. this is a personal preference. Just choose one.

Instead of redirecting when we first find a problem, I append all changes to the URI, so that users (and bots) only receive one 301 Redirect.

Below is the httpmodule code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web;
using System.Text.RegularExpressions;

namespace dotnamics_mvc.HttpModules
{
    public class SeoFriendlyHttpModule : IHttpModule
    {
        public void Dispose()
        {
        }

        public void Init(HttpApplication context)
        {
            context.BeginRequest += new EventHandler(context_BeginRequest);
        }

        void context_BeginRequest(object sender, EventArgs e)
        {
            HttpApplication app = (HttpApplication)sender;

            string url = (app.Request.Url.Scheme + "://" + app.Request.Url.Authority + app.Request.Url.AbsolutePath);
            bool redirect = false;

            // check for trailing /
            if (url.EndsWith("/") && app.Request.Url.AbsolutePath != "/")
            {
                redirect = true;
                url = url.Substring(0, url.Length - 1);
            }

            // check for capital letters
            if (Regex.IsMatch(url, @"[A-Z]"))
            {
                redirect = true;
                url = url.ToLower();
            }

            // check for default routing (Index)
            if (url.EndsWith("/index"))
            {
                redirect = true;
                url = url.Substring(0, url.Length - 6);
            }

            // check for www
            if (url.Contains("www."))
            {
                redirect = true;
                url = url.Replace("www.", "");
            }

            if (redirect)
                Redirect301(app, url + app.Request.Url.Query);
        }

        private void Redirect301(HttpApplication app, string location)
        {
            // set status to 301 - Perm Redirect
            app.Response.StatusCode = 301;
            app.Response.Status = "301 Moved Permanently";
            app.Response.StatusDescription = "Moved Permanently";
            app.Response.AddHeader("Location", location);
            app.Response.End();
        }
    }
}