Quora&39's new API helps with projects such as Andrew Brown&39's Chrome extension for showing Quora notifications.

Quora, an increasingly popular question-and-answer site with a social networking angle, has released an application programming interface that opens the door for third-party software to use the service.

The API, announced Friday, has very limited features and is only an alpha release that the company doesn't promise will remain stable. But it's an important milestone nevertheless for the company as it charts a course through the complexities of building a business on today's Net.

That's because an API, if rich enough, means people using a service don't necessarily have to use that services' Web site. For example, Twitter's API is powerful enough that many people employ software such as TweetDeck or Seesmic to use the short-message service. That helped Twitter grow fast into something of a utility on the Net and saved the company money on Web servers that show pages to visitors. But it also means the company can't as easily choose one obvious Web business model, showing online advertisements--and Quora's subject-specific discussions could be a nice match for targeted advertising.

Of course, a full Quora API doesn't preclude a Web ad business model. Enabling third-party use of the service could accelerate its growth, and if the site is still compelling enough to use directly, a stronger advertising business could follow. And fast growth is important for the site: Facebook, the social network where millions already spend a lot of time online, has a question and answer service of its own.

So far, there's not enough of an API to bypass Quora's Web site. According to a post by Quora engineer Edmond Lau, the API exposes information about the number of people a Quora user follows, how many people follow that user, and how many inbox messages and notifications the Quora user has. So there's not enough at present to build a full-fledged Quora app that would have let people do things like publish and answer questions, follow new people, and vote on the merits of a various answers.

That's enough to help out programmers, though. Lau specifically pointed out Andrew Brown's Chrome extension and Jason Wiener's Firefox extension as applications that would be able to use the API.

Those programmers were happy with the move. "Awesome work Edmond! Thanks again for the help," Wiener said in a response to Lau's post. And Brown said, "This is a great step forward for the developers community (and soon the Quora developers community). I'm excited to see what other products come from this."

It's important that Quora began adding an API, but it's not a big suprise.

"When there are enough users and content on Quora that an API would be really useful, we'll almost certainly add one," said Quora employee Charlie Cheever in a Quora question in December 2009.

"For right now, we'll probably focus on the Web interface since that's how we think most people will use the product, at least to start. Another reason we probably won't do an API for a little while is that the interface into the product is changing frequently in big ways right now," he said, "and APIs that aren't stable are hard to use effectively."

Via Read Write Web