RevCanonical is url shortening with a twist. Instead of creating its own super short versions of links, it checks to see if the link owner has published a shortened version of the given page using HTML link element. If not, we just return the original URL. And you should bug the link owner about providing a better alternative.
URL shorteners are as problematic as they are useful. They create SPOFs, that over any meaningful timeframe are guaranteed to create data loss, eroding the historical record. And then there are the privacy concerns. And the usability ones.
RevCanonical searches the referenced resource for a link element that looks like
(RevCanonical will also search for relationships advertised using
<link rev="canonical" type="text/html" href="...">(i.e. a link element advertising "I am the canonical URL of that page over there" or colloquially the "reverse canonical of that URL")
<link rel="alternate shorter" href="...">or truth be told any link rel including the string "alternate short*")
There is also an API version, which returns just the resulting URL.
Shorten (drag to your browser toolbar)
Well sort of. There aren't many sites which support it, but there should be. And there are more everyday.
Check out the RevCanonical blog for more details about who support
rev="canonical", and why.