While Web app frameworks are nothing new, Yahoo claims Mojito is different because it addresses the problem of delivering content to devices that have weak or intermittent connections, said Bruno Fernandez-Ruiz, chief architect with Yahoo's platform technology group.

Developers use Mojito to write apps using Javascript, HTML and CSS that can run both on the client, using an embedded Javascript engine, and on the server, using the emerging Node.js platform. That means that if bandwidth is limited, an app can switch between rendering on the client and rendering on the server, providing a better experience for the user, Fernandez-Ruiz said.

Yahoo in November and is making the code available to developers this week under an open-source BSD license. It positions Mojito as a way to free developers from what it calls "closed, proprietary" platforms such as Apple's iOS, and from having to choose which platform to develop for.

It sees Mojito being used primarily by publishers to deliver newspapers and magazines, and for interactive ads. Yahoo has released a few Mojito apps to show what it can do, including , an iPad app for reading articles from various sources.

It's part of a wider Yahoo project called Cocktail, to build a Web presentation platform for devices. The Cocktail project also includes Manhattan, a Yahoo-hosted server environment based on Node.js where developers will be able to host their applications.