Google has said it plans to release a free online spreadsheet program to compete with Microsoft’s Excel.

Google Spreadsheets will allow users to import and export spreadsheets in the .xls format used by Microsoft Excel and the more generic .csv (common separated values) format.

Through a Web browser, users in remote locations will be able to view and simultaneously edit data. The software is platform-neutral, meaning it can be accessed using a number of browsers, including the open-source Firefox, Microsoft's Internet Explorer or Apple's Safari.

Google will accept sign-ups on its website from a limited number of beta testers starting at 9 a.m EDT/1 p.m. GMT Tuesday, a Google spokeswoman confirmed.

"This further proves the legitimate usefulness of software-as-a-service applications," said Tom Snyder, president of iNetOffice. The startup makes a free Web-based word processor called iNetWord.

Charlene Li, an analyst with Forrester Research, said next-generation Web applications such as Google Spreadsheets and Writely, an online word processor acquired by Google in March, provide much of the functionality of Microsoft Office but are not yet credible replacements.

"Google Spreadsheets is not an effort to replace Excel. And if you tried to print out stuff you wrote in Writely, it would come out all ugly," she said. "Look at Web-based e-mail. We've had it for 10 years, but Outlook still reigns supreme.

"Eventually these products will get there, but not today."

Google was not the first company to release a Web 2.0 counterpart to Excel. A startup called iRows also offers a free online spreadsheet program.

San Diego-based Ajax13, a startup founded by Internet entrepreneur Michael Robertson, also has a beta of a free Web spreadsheet editor called ajaxXLS.

AJAX13 is the closest so far to having a full lineup of productivity applications that can challenge Microsoft Office. Besides ajaxXLS, the company also offers an online word processor called ajaxWrite, a drawing program called ajaxSketch and a hosted video editor called eyespot.

It plans to release a PowerPoint-like presentation program by the middle of the year, according to Robertson, who founded MP3.com and is also chairman of desktop Linux provider, Linspire.

Robertson said that AJAX's applications were gaining fans - more than 10,000 unique users a day - because Microsoft is stuck: reluctant to cannibalise existing Microsoft Office revenues by cutting prices or by beefing up its Office Live family of Web-based applications, which despite their name, don't yet provide any of the features of Microsoft Office.

"The beauty is that we are attacking Microsoft right at their heart," Robertson said.

Unlike AJAX13, which is marketing its wares directly at end users, Snyder hopes to sidestep competition from Microsoft and Google by inking partnerships with other hosted software providers who need word processing capabilities within their applications.