Twitter's t.co link shortening service

Twitter has rolled out their new t.co URL shortener.

At first I was a bit worried about this from an SEO point of view because to change the referrer to a t.co url, twitter has to return a 200 HTTP code and use an html refresh or javascript redirect. This would have been an seo disaster.

Luckely, after going through the twitter dev docs I found this:

https://dev.twitter.com/docs/tco...:

"t.co currently handles redirections by context and known user agents. We've taken care to preserve original referrers in all contexts where they are reliably provided."

Turns out Twitter is using different types of redirects based on the referrer and the type of browser. Googlebot for example will receive a normal 301 redirect. A human visitor using Firefox or internet Explorer will get the new t.co referrer-changing-redirect.