NEW YORK - A quiet revolution is transforming life on the Internet: New, agile software now lets people quickly check flight options, see stock prices fluctuate and better manage their online photos and e-mail.
Such tools make computing less of a chore because they sit on distant Web servers and run over standard browsers. Users thus don't have to worry about installing software or moving data when they switch computers.
And that could bode ill for Microsoft Corp. and its flagship Office suite, which packs together word processing, spreadsheets and other applications.
The threat comes in large part from Ajax, a set of Web development tools that speeds up Web applications by summoning snippets of data as needed instead of pulling entire Web pages over and over.
"It definitely supports a Microsoft exit strategy," said Alexei White, a product manager at Ajax developer eBusiness Applications Ltd. "I don't think it can be a full replacement, but you could provide scaled-down alternatives to most Office products that will be sufficient for some users."
Ironically, Microsoft invented Ajax in the late 90s and has used it for years to power an online version of its popular Outlook e-mail program.
Ajax's resurgence in recent months is thanks partly to its innovative use by Google Inc. to fundamentally change online mapping. Before, maps were static: Click on a left arrow, wait a few seconds as the Web page reloads and see the map shift slightly to the left. Repeat. Repeat again.
"It's slow. It's frustrating," said frequent map user Fred Wagner, a petroleum engineer in Houston. "We're all getting spoiled with wanting things to happen."
So he sticks with Google Maps these days. There, he can drag the map over any which way and watch new areas fill in instantly. He can zoom in quickly using an Ajax slider.
No more World Wide Wait.
"Everybody went, `Ooooh, how did they do that?'" said Steve Yen, who runs a company developing an Ajax spreadsheet called Num Sum. "It turns out the technology's been there for awhile."
Jesse James Garrett, an Adaptive Path LLC usability strategist who publicly coined the term `Ajax' 10 days after Google Maps launched in February, said such examples "convinced a lot of Web designers to take another look at something they may have previously dismissed as experimental."
Until recently, Web mail meant sending forms back and forth online. Check an item to delete and hit a button. A remote mail server receives instructions and responds with an entirely new page, which is missing only the one deleted item.
Enter Yahoo Inc. and an interface it is testing using technology from an Ajax pioneer it bought, Oddpost. Delete an item this time, and Ajax reconfigures the page immediately without waiting for a response.
Open a message to read, and the browser fetches only the message's body - it already has the subject line and other header information and doesn't have to waste time duplicating that data.
Yahoo also is developing an Ajax tool that instantly updates flight options as travelers narrow their choices of airports, airlines and travel times.
This summer, Time Warner Inc.'s America Online Inc. started using Ajax to let users rearrange, display and switch photo albums with fewer clicks.
And last week, Dow Jones & Co.'s MarketWatch began embedding news articles with stock quotes updated several times a second, blinking green and red as prices fluctuate.
"A Web page takes longer to load than that," said Jamie Thingelstad, MarketWatch's chief technology officer. "Your computer would just be hung."
Microsoft, which uses Ajax in a new map offering and an upcoming Hotmail upgrade, is even starting to build new tools to promote Ajax development - even as it pushes a next-generation alternative.
The alternative technology, known as XAML, will permit even richer applications over browsers. Alas, unlike Ajax, it will run only on Microsoft's Windows computers - no Macs, no Linux.
Startups, meantime, are embracing Ajax for Office-like tools. Such applications won't replace Office but could find a niche - parents collaborating in a soccer league could jointly update a Num Sum spreadsheet with scores, while users too poor to buy Office or students always on the go could compose a letter from anywhere using Writely word processor.
Scott Guthrie, who oversees the Microsoft Ajax tools called Atlas, believes Ajax has a future but not one at odds with Microsoft's.
"Ultimately when you want to write a word processing document or manage a large spreadsheet, you are going to want the capabilities ... that are very difficult to provide on the Web today," Guthrie said.
Computer-intensive applications like Adobe Systems Inc.'s Photoshop image editor and high-end games won't come to browsers anytime soon.
Even Google had to create desktop mapping software, called Google Earth and requiring a download, to permit 3-D and advanced features.
"Ajax cannot do everything," said Bret Taylor, who oversees Google's mapping products. "Web applications have a way to go."
Other limitations are intentional. For security reasons, a browser cannot seamlessly access files or other programs on a computer. And, of course, Web applications require a persistent Internet connection - making work difficult on airplanes.
Usability expert Jakob Nielsen also worries that loss of productivity - a minute here, a minute there, multiplied by thousands of employees - will offset any savings in installation costs.
"When you do a lot of transactions, you want something that's optimized for the transaction, not something optimized for information browsing," he said.
Among other criticisms, developer tools for Ajax aren't as mature as those for one of its chief rivals, Macromedia Inc.'s Flash. And many Ajax programs don't work well beyond Microsoft's Internet Explorer and Mozilla's Firefox browsers.
Yet Web-based applications are increasingly appealing at a time separate computers for home, work and travel are common and people get used to sharing calendars and other data with friends and relatives.
Ajax can make those experiences richer.
"There's a lot of power sitting on that Web browser ... that people are just tapping into," said White of eBusiness Applications. Web developers "are beginning to push its limits in terms of creative uses and new applications."