Google is using its first worldwide Developer Day today to launch Google Gears, an open source technology for building web applications that can work offline.

In addition the company will unveil plans to work with other vendors to mould standards that would provide developers with consistent application programming interfaces (APIs) for building offline functionality into web-based applications.

The free Google Gears technology builds on the existing programming models for the web and adds new JavaScript APIs for data storage, application caching and multi-threading features, the company said. The Gears tool will work with all browsers that run on the Windows, Macintosh and Linux operating systems, it added.

An early version of Google Gears is now available, the company said.

The Google product joins a burgeoning group of technologies, including the Apollo tool from Adobe and the Silverlight technology from Microsoft that aim to make "the client side of web applications compelling again," said Jeffrey Hammond, an analyst with Forrester Research.

Indeed, Eric Schmidt, Google chief executive said in a statement that Google Gears is "tackling a key limitation of the browser in order to make it a stronger platform for deploying all types of applications and enabling a better user experience in the cloud".

Hammond said it has been several years since the industry has seen "significant innovation around the core of the browser itself," which Google is aiming to do with Code Gears.

"In theory, if this works you'll be able to have a browser and nothing else [to] do the things that now requires Apollo on the desktop or Silverlight in a [media] player," Hammond said.

To highlight how the new Gears technology can work, Google on Thursday is making its Google Reader feed reader available with offline capabilities that were created using the new technology.

Kevin Lynch, senior vice president and chief software architect at Adobe, said his company will join Google in the effort to develop a standard cross-platform, cross-browser local storage capability. The Gears API will be available in Adobe's Apollo tool that enables web applications to run on the desktop, he added.

In related news, Google also will announce at the developer event that its Google Web Toolkit, a Java software development framework for writing Asynchronous JavaScript and XML (AJAX) applications, has been downloaded one million times since its release in May 2006.

The company said that it also plans to release the Google API Library for the web toolkit with support for Google Gears.

Google also will release the Google Mashup Editor, an experimental online code editor for building mashups, the company said. It is aimed at developers familiar with HTML and JavaScript.