Web 2.0 apps often come with an API and an AJAX interface. I wonder if that’s a correlation, not just a coincidence.

An API is a standard set of procedures for connecting to an application’s backend. AJAX is a programming method for connecting Javascript, running in the user’s browser, to an application’s backend. See the similarity? Maybe it’s easier to build AJAX into an app that already has an API and vice-versa.

For example, Paul Rademacher was the first to build a Google Maps mashup (it was with Craigslist), something that was never possible with MapQuest. And this was before Google offered a mapping API. I assume it was because Google Maps’ AJAX model let Paul see the interactions between the browser and the server and hook into them.

Likewise, libgmailer is a scrAPI interface to Gmail, no doubt made possible by Gmail’s AJAX interface. There’s no API for Gmail, but you can use libgmailer.

The programmers working on our personal finance web app have developed very modular code that allows the AJAX front end to access the database back end through a set of internal APIs. This will make it all the more easy to offer a public API.