Web API Lifecycles and Hypecycles

I've long been fascinated by the explosion of APIs over the past years, captured by the excellent ProgrammableWeb site.

Curious about how categories were evolving over time, I mined ProgrammableWeb's index for interesting patterns. I focused primarily on categories with at least 50 APIs, dividing them up into semesters from the second half 2005 to the first half of 2010. One important detail to be aware of: the PW index includes the last modified date of the API, not its creation date. So think of these graphs as a measure of activity in a particular category. For example an API may have been created in 2006 but if it was updated in 2010 it will count towards that last bar on the graph.

So what's hot? Social APIs, unsurprisingly, show a feverish activity: every site is busy creating or expanding their offerings in this space.

Enterprise APIs too are seeing a lot of movement.

Encouragingly, so is Shopping. A harbinger of an economic turnaround, or just wishful thinking? :-)

What about up-and-coming API categories to watch? Of the ones with over 30 APIs Travel and Utility have seen the most movement over the last year and a half.

Here are the remaining 13 categories with 50 or more APIs. Other strong performers include Government, Telephony, and Tools. Categories in relative decline? Reference and Video.