APIs, with which external developers can build applications on top of existing functionality and data, are becoming an important element of many new companies and services on the web. New business and revenue models arise from this trend. But too often APIs are thought of as 'just another interface'. Therefore it's good to see things are changing.
"I was surprised to hear, though, how many of these companies build their own public-facing web sites second, by building on top of a web services API they develop first. The act of developing a public API, then, is not one of designing and testing various API calls -- instead, all they have to decide is which of their existing method calls they want to expose to the public. They already know the methods work, because if they didn't, the public web app wouldn't work, either."
We will be releasing a public API for Eccky soon, and are already using it for the mobile Eccky client, but I often wondered why we did not use the API for our website (and more) for the exact same reason as given above. And yes, I already know the answer to that question, we don't have to because we're not external developers, but I feel that's the wrong answer from a (future) business point of view.