From beginning of the Internet people have shared URLs with each other .Bit.ly, Tr.im,and Goo.gl. ow.ly are some services that takes long URLs and squeezes them into fewer characters to make a link that is easier to share, tweet, or email to friends.The URL aliases are handy, but they pose a risk, too: Since short URLs give no hint of the destination, attackers can exploit them to send you to malicious sites. A person might send the short URL to a you. When the short URL is clicked, the website looks up the longer URL and redirects the user to the longer URL.The most obvious risk associated with URL shortening is that it's difficult to know where the URL will take you, until you click it.
There are several sites that you can use to view a long URL by cutting and pasting a shortened link like longurl.org.Programs such as TweetDeck include options in their settings to display previews of shortened URLs. With such a setting enabled, clicking a shortened URL within a tweet brings up a screen that shows the destination page’s title, as well as its full-length URL and a tally of how many other people have clicked that link. With this information at your disposal, you can make an informed decision about whether to click through and visit the actual site.
When you create a shortened address with the TinyURL service, for instance, you can choose an option to create a preview version so that recipients can see where it goes before clicking. Conversely, if you’re considering visiting a TinyURL link, you can enable its preview service (tinyurl.com/preview.php) to see the complete URL. For the TinyURL previews to work, though, you must have cookies enabled in your browser.
ExpandMyURL and LongURLPlease both provide Web browser plug-ins or applets that will verify the safety of the full URLs behind abbreviated links from all the major URL-shortening services.LongURL Please supports 80 shortened services . Rather than changing the shortened links to their full URLs,however, ExpandMyURL checks destination sites in the background and marks the short URLs green if they are safe.Goo.gl, Google’s URL-shortening service, provides security by automatically scanning the destination URL to detect and identify malicious Websites,and by warning users when the shortened URL might be a security concern. Unfortunately, Goo.gl has limited application because it works only through other Google products and services.Sucuri.net is another free online service to retrieve the original URL from a short URL shortened using any of the service like bit.ly, tinyurl.com, su.pr etc .Untiny which retrieves the original URL from short URL of tinyurl.com or bit.ly only.