Google's quest to keep browser-based applications running while offline is expanding to where it may be needed most: mobile devices.

A version of the Google Gears browser extension software is available to developers, according to a Monday blog posting by Google Mobile Product Manager Charles Wiles. So far it's available only for Microsoft Internet Explorer Mobile on Windows Mobile 5 and 6 devices, but there will be versions for other platforms, including Google's own Android system, Wiles wrote.

Google Gears, still in beta testing, lets people continue to work with Web-based applications after they've gone offline. Data and documents are saved on the device so users can see and work on them any time. Gears is already available for desktops and notebooks, with versions for Internet Explorer on Windows XP and Vista, and for Firefox on XP, Vista, MacOS and Linux. Gears for Mobile is a port of that software.

Although notebook PC users sometimes fire up their systems where wired or wireless Internet access isn't available, users of handheld devices with cellular data services often are at the mercy of carrier networks where coverage comes in and out. Using Gears to cache data on devices, developers can create Web-based applications that not only are usable completely offline, but also are more responsive where networks suffer delays, according to Google.

Users can download Google Gears for Mobile, and developers also can get an API (application programming interface) to add it to their software. A few mobile applications already use Gears for Mobile, including Buxfer personal-finance software. Zoho, which makes a suite of Web-based applications including word processing, spreadsheet, presentations and organizer, also is working with Gears for Mobile.

With Zoho Writer word-processing software, users can view their documents on Internet Explorer Mobile both online and offline. Zoho will offer mobile document editing later, according to a company blog.