Tinyurl.com clone

Need a tinyurl clone, with a nice, simple design. But there is a bit of twist to it, users will be able to choose if they want the site short url redirects to be masked, so that users see short url in their address bar. For example if short url is [login to view URL] and the click it, when they come to the page short url stil is visible in address bar (similar like you have masking if you 301 redirect domain to another site in Godaddy). There are some tinyurl clone scripts out there, you might want to check that out.