Sept. 1 (Bloomberg) -- Google Inc., owner of the most popular Internet search engine, will offer its own free Web browsing software to challenge Microsoft Corp.

The browser, known as Chrome, will be available as a test version for download tomorrow in more than 100 countries, Mountain View, California-based Google said today in a blog post. The software is designed to isolate flawed Web pages so users can close them without shutting down the entire browser.

Google is battling Microsoft for customers who use a browser for tasks such as e-mail, calendars and word processing, applications that have traditionally been handled with software stored on a computer. A Web browser could help Google lure users to its programs and search engine, said analyst Roger Kay.

``This gives Google another opportunity to protect its flank and to create a new branding position,'' said Kay, president of Endpoint Technologies Associates in Wayland, Massachusetts. ``The browser is a broader platform than they currently have.''

The market for Web-based software may reach $160 billion by 2011, including revenue from advertising, Merrill Lynch & Co. said in a May report.

``We realized that the Web had evolved from mainly simple text pages to rich, interactive applications and that we needed to completely rethink the browser,'' said the Google blog post, credited to Sundar Pichai, vice president of product management, and Linus Upson, engineering director.

Market Share

Microsoft's Internet Explorer has about 72 percent of the Web browsing market, followed by Mozilla Corp.'s Firefox with 20 percent and Apple Inc.'s Safari with 6.4 percent, according to research firm Net Applications of Aliso Viejo, California.

Microsoft, based in Redmond, Washington, released a new version of Internet Explorer last week for testing. The software lets users control whether it saves the sites they've visited.

Mozilla, also based in Mountain View, said last week it extended an agreement through 2011 to keep Google as its default search engine. The company is owned by the non-profit Mozilla Foundation.

Like Firefox, Google plans to release Chrome as open-source software, meaning programmers can edit the code and add their own features.

Google fell $10.49, or 2.2 percent, to $463.29 on Aug. 29 in Nasdaq Stock Market trading. The shares have declined 33 percent this year.

To contact the reporter on this story: Crayton Harrison in Dallas at tharrison5@bloomberg.net.

Last Updated: September 1, 2008 18:58 EDT