The Qwerly API lets developers easily link together users' various social network accounts. For example, given Tim O'Reilly's Twitter username, it can reveal his public profiles at other services like Facebook, Flickr and Plancast. Why is this interesting? Bridging the barriers between different social networks weakens the lock-in effect that makes it tough to opt out of popular services.

If you decide you don't want to participate on Facebook, right now that means losing touch with all of your friends still using it. With Qwerly, a service could let you interact with your entire social network in one place, even if some people are most active on Twitter and others on Facebook.

It's a bit like phone number portability. In the bad old days, if you changed phone company you were given an entirely new number, with all of the hassle of telling your friends and colleagues and changing business cards and stationery. By making a connection between you and your friends' accounts on different networks, Qwerly hopes to make switching to a new service painless.

I spoke to Qwerly's founder Max Niederhofer about his plans for the service. He said its mission was to be "at the center of the Rebel Alliance against Facebook - we want to power the federated social web". He continued:

"The motivation to build Qwerly was really the question 'what do we need to build a decentralized social web platform?' and what we came up with was 'first, we need to find out how profiles are connected', i.e. consolidating identities across profiles. We looked at what had happened there in terms of open protocols, like webfinger, and figured things weren't moving fast enough."

Originally he was planning on building his own Friendfeed-like service, but one that would instantly show your friends' updates rather than relying on you to laboriously enter all your account details before you'd see any benefits. As he looked at what it would take to build the system, he realized the hardest step would be gathering and linking accounts across social networks, and by sharing the results as an API he'd create a platform for other startups to build their own services on. Services like the HoverMe social browsing plugin and the DuckDuckGo search engine are already taking advantage of the interface to enrich the results they offer.

Any service that deals with people's personal data raises concerns about privacy, so I asked Niederhofer how they were different from services like Rapleaf that have attracted intense criticism.

His response was that "the difference between what Rapleaf was accused of and what we're doing is that Rapleaf was commingling social data and cookie-based data. While social media data isn't yet construed as personally identifiable information, it definitely serves to identify a person. So if you mix cookies and e.g a Facebook ID, you are effectively de-anonymizing web traffic." With the focus on information gathered only from public Web profiles, with no use of cookies or other data sources, he sees the service as just aggregating freely available information in a novel way.

Though it's still early days for the platform, I'm hopeful it can add social context to many different applications, for example transforming the humble phone address book into something much richer.

This is an area that Union Square Ventures' Fred Wilson has been discussing a lot recently. Wilson's colleague Albert Wenger has complained to Niederhofer about his phone: "I open up the address book, it looks like my old Palm - and I mean Pilot, not Pre!" With rich information about all your contacts' social profiles, it's easy to imagine something like Gist tightly integrated with your address book.

What do you think? Is this service going to open up a new world of innovative applications based on federated social information? Are you more concerned about how much personal information we're making publicly available on our profiles?

X Wing photo by Psiaki