Mozilla developers are in the early stages of building an open application interface for smartphones and tablets called WebAPI.

The significance of the effort is that WebAPI could become a way for smartphone developers to write one application that would run anywhere, including on Apple's iOS, Windows Mobile and Android devices, at least according to one interpretation by ConceivablyTech.com .

The WebAPI project, described as lasting three to six months in the initial stage , would be a set of HTML5 Application Programming Interfaces (API) that would provide web-based application interfaces accessible by any HTML5 smartphone or tablet.

Richard Tibbett, a platform architect for Opera Software, posted an unofficial draft document related to the WebAPI project. The document addresses the messaging technology needed for the process to function.

Tibbett suggested in a message to other developers that his concept for WebAPI would allow "any native app, OS or website to offer its own API...We allow free-market forces to naturally select the best APIs offered for any given problem as they spring up."

"What comes to be most used...is up to the market to decide: millions of Web apps deciding which API's to plug in to...The model works in the interests of a constantly evolving Web," he writes.

Bloggers noted that for WebAPI to work, it will depend on Google , Apple and Microsoft to adopt it. That won't be an easy task, they noted.