GwaGwa is described as 'Shorten & Protect Your Links'. There are more than 100 alternatives to GwaGwa, not only websites but also apps for a variety of platforms, including Windows, Linux, Self-Hosted solutions and Mac. The best alternative is Kutt, which is both free and Open Source. Other great sites and apps similar to GwaGwa are bit.ly (Freemium), Polr (Free, Open Source), YOURLS (Free, Open Source) and Catbox (Free).
You may have heard of projects like bit.ly where you paste a long URL and the service spits back a shorter one you can share with friends and colleagues. cmpct.io is a bit like bit.ly but it differs in a few ways...
Shrinky is a free URL forwarding service (URL redirection) allowing anyone to take any existing URL and shorten it. You can custom your link - set password, number of uses, expire date, make it public or private and choose desired name.
PHPurl is a simple script that allows users to make a shorter url. This is great when you have a long url (ex: http://blondish.net/scripts/phpurl/) and you want to make it shorter for SMS or other things that have a limit on how many characters you can type (ex: Twitter).
Custom URL shortening service that allows you to use your own domain or subdomain. Your users will know they are clicking on trustworthy links because it's your domain. Only your authorized users can create links on your short URL service.