TinyURL is a web page redirection service that substitutes short aliases for longer, presumably hard to remember urls. Created in 2002, it has been of limited use on the web and has occasionally been misused by affiliate or scam websites that wanted to get clickthroughs without showing their domain identify. [All domains can be tracked back to their owner through the domain registration system administered by VeriSign].

The explosive growth of Twitter has dramatically increased the visibility of the tinyurl service because Twitter, with its limit of 140 characters per posts, doesn’t want a lengthy url to take up too much of the limited space. Typically tweets now contains dozens of tiny urls as the user references followers back to expanded content, usually on a blog.

It has not gone noticed in the SEO community that Twitter back links can be valuable in helping a website increase its page reputation, especially with Google. It’s not uncommon to see Twitter links  appearing in the first page of results to “link://www.yoursite.com” Google searches, which displays the list of inbound links to your site. So many webmasters would like to use Twitter to help increase the reputation of their sites.

The rub is if the back link is in the form of a tiny url, you can pretty much forget about getting any page rank boost from the link. As a result of the spotty reputation of tiny urls in the past, Google devalues any tiny url back links.

Twitter doesn’t automatically rewrite all urls as tiny urls. We’ve tested shorter urls up to a length of 31 characters and found the original links preserved. At the same time, we have found links of 41 characters to be rewritten as tiny urls. We’ve also found that longer “non working” urls not to be rewritten, so they must be employing some kind of test to see if the page displays. It doesn’t not seem to matter how much content precedes the 31 character url, as long as it stays within the 140 character limit. We haven’t had the time to test this extensively, so we’d be interested in hearing what other Twitter rewrite testers have found.