Bit.ly and TinyURL provide free link shortening services.
Bit.ly
You do not need to create an account or pay to use Bit.ly, although there are account options.
To shorten a link without an account, paste the link into the box labelled 'Shorten your link' and click the Shorten button.
You can also create a free account by clicking 'Get Started for Free' and scrolling down to find the free account option. This allows you to also create custom short links and use the Bit.ly web browser extension.
TinyURL
TinyURL is a totally free service and does not have accounts. You can also create custom shorten links and add a bookmarklet on your bookmarks toolbar to create a TinyURL from any webpage.
