Firefox with Greasemonkey: TinyURLs and kin are great for packing links into small spaces, but not so great at revealing where the link will take you. Remove the mystery with TinyURL Decoder.
We’ve covered several methods for peeking into TinyURLs before. LongURL is a website and Firefox extension that expands compacted URLs with a mouseover, Tin Foil Hat is a Greasemonkey script that provides the same mouse over transparency, and Embiggen is a bookmarklet that expands all the links on the page to their true length. While they all get the job done, they all require some sort of user input whether by using a mouse over to read the real URL or activating a bookmarklet every time you want to see the source URLs.
Tiny Decoder is a Greasemonkey script with seamless integration. When the script is active, compacted URLs from 13 URL shrinking services are automatically converted to their source URLs. No resource hogging extensions or bookmarklets you have to interact with, just automatic and seamless replacement. TinyURL Decoder is a free Greasemonkey user script and works wherever Firefox does.