CHeriCoS

As recently announced, the URL-shortener tr.im, is dead. So all shortened URLs will be gone shortly too. This is a good example why you should not rely on such service when you have something to write/link/post that should be available (and reliable) in the long term. Persistent Identifiers (PID) in Cultural Heritage like DOI, URN, PURL or other do have something in common with those URL shorteners. They are man-in-the-middle-services: id -> resolver -> resource. A resolver in the middle is always necessary to decode a given PID and point to a resource. The institutions and companies behind them guarantee that there will be services to do the resolving forever, but what if a company shuts down or an institution changes? What if in ten years OCLC decides to get rid of PURLs? Will there be someone to take over? URL shorteners do not claim that the shortened URLs will be redirected forever. But for example bit.ly says that they are "in the process of developing an archive system to make sure that links are available beyond our systems" (http://bit.ly/pages/faq/). So I think the "normal user" assumes his links will work the next few years and will be very bothered if they are not someday. But if you don't mind, you can check out these alternatives:

• TinyURL - The first(?) URL shortener is still online.
• Bit.ly - The default URL shortener of twitter.
• Redir.ec - A new service that claims to be very fast.
• u.nu - The shortest urls. Period.

Need more? Check out mashable's post about 90+ URL Shortening Services. Update 08-12-2009: tr.im is resurrected! Because of the overwhelming feedback they got after announcing the end they restored tr.im and re-opened its website. Sounds like a big marketing joke to me ...