Popular URL Shorteners services

URL shortening dates back at least to 2001, before Twitter launch. TinyURL was launched in 2002, and was the first notable URL shortener service. URL shorteners main service is to transform a long URL to a smaller URL. Some of these services provide statistics about the number of clicks on the shortened URL.

• To make an URL more readable / aesthetic.
• To limit the size of a message. Twitter is the service that comes to mind. But some other instant messages services or to generate simple QRCode might also require a small URL.
• To identify traffic sources and get statistics on specific links.

Features

Redirect type web links can be redirected to the long URL with several techniques. Using HTTP redirect with either code 301 for permanent redirection or code 302 for temporary redirection. The 301 redirection is good for SEO to give credits to the link. While 302 might be good if the service provide th ability to change the long URL it points too.

Preview URL some services does not directly redirect you to the long URL you gave; but instead ask you if you want to be redirected and display the full URL. This is an important feature to avoid being redirected to some unsecure website or to detect affiliate links.