Custom pipeline for URL redirect in Sitecore

Sample code snippet

    public class Redirect : HttpRequestProcessor
    {
        public override void Process(HttpRequestArgs args)
        {
            try
            {
                Assert.ArgumentNotNull(args, "args");
              
                if (Context.Item == null || Context.Database == null || args.Url.ItemPath.Length == 0 || args.Url.FilePath.Contains("/sitecore"))
                {
                    return;
                }
                if (Context.Database != null)
                {
                    string rawURL = string.Empty;
                    rawURL = Sitecore.Context.RawUrl;

                    // you can write your custom logic here.

                }
            }
            catch (Exception ex)
            {

            }

        }

Now you can add this pipeline in "httpRequestBegin" section inside web.config
See sample

<httpRequestBegin>
      <processor type="MyApp.Redirect, MyApp"/>
</httpRequestBegin>