Typically, at some point in the life of successful HTML-based web app, someone gets the idea to convert it into a web API. There are lots of reasons this happens. Some want to “unleash the value” locked inside a single application to make the underlying functionality available to a wider audience. There might be new opportunities in other UI platforms (e.g., mobile devices, rich desktop apps, etc.) that don’t support the HTML+CSS experience. Maybe someone has a new creative idea and wants to try it out. Whatever the reasons, a web API is born.
