Most major Antivirus Companies have link scanners but there are just limited to just direct links, but in the age micro-blogging url’s are being shortened using services like tinyurl, Bit.ly and many more it tough to know the exact destination of the URL.

You can avoid phishing, malware, and viruses attacks by examining short URLs before visiting them using simple tools and Browser addons that have been listed below.

1. LongURL – LongURL supports many URL shortening services like tinyurl.com, is.gd, ping.fm, ur1.ca, bit.ly, snipurl.com,etc and many more.Check the list of supported URL Shortening services here.But this addon does not scan the url but just shows the destination URL.LongURL also provides a Firefox Addon that you can use to see the actual destination of the shortened url, the addon shows a tooltip windows with the destination URL on hovering the mouse pointer over the shortened URL.
   
   

   There’s also a GreaseMonkey Script that you can use with Firefox, incase you are already have GreaseMonkey installed.

   Download LongURL Firefox Addon or LongURL GreaseMonkey Script.

2. Finjan’s SecureBrowsing – Scans the current form of a page as it available on the Web now, in real-time and Detects malicious content based on code analysis and provides a rating beside the link.It has addons for Firefox 1.5 and above and Internet Explorer 6.0 or 7.0.
   It currently supports the following services
   • Search Engines: Google, Yahoo, Live (msn)
   • Advertising systems: Google Adsense
   • Online email applications (AJAX-based): Gmail, Yahoo mail, Hotmail
   • Popular Websites: Twitter, MySpace, Digg, Slashdot, Blogger

   Download Firefox Addon -    Download IE Addon [ Source ]

3. AVG LinkScanner
   Incase you are using a free antivirus that does not have a linkscanner feature you can try out AVG LinkScanner which looks for threats in every search result and every link to a web page – right as you click on it. It works on Internet Explorer, Firefox and Opera can run alongside your current anti-virus software providing an additional layer of protection.Download AVG LInkScanner

Last but not the least, It is always better to check the source before trying to access an external link.