Mozilla has kick-started development of a Metro-style version of Firefox for Windows 8, Google has committed to doing the same and Opera Software said yesterday that it's looking into the matter.
Those three browser makers would be chasing Microsoft, which has a five-month head start, having already built several iterations of Internet Explorer 10 (IE10) that run on both the Windows 8 traditional desktop and in the operating system's new Metro touch-first user interface (UI).
Mozilla, which first said a month ago that it would build a "proof-of-concept" edition of Firefox for Windows 8's Metro UI, recently revealed more details of the project.
According to Firefox engineer Brian Bondy, Mozilla began actual development of a Windows 8 browser last week.
It turns out that Microsoft will allow hybrid desktop-Metro apps, but will limit that third category -- after classic x86/64 Windows programs and Metro-only applications -- to something the Redmond, Wash. giant dubbed "Metro style enabled desktop browsers."
"Firefox will fall into the third category, meaning you can run Firefox as a desktop application, and you can run it as a Metro application," said Bondy in a March 9 post to his personal blog.
Metro style enabled desktop browsers can run outside the normal Metro sandbox and have access to most classic Windows APIs (application programming interface), as well as the new WinRT API, the backbone of the Metro side of Windows 8 application development.
The category also gets an important pass from Microsoft: A Metro enabled desktop browser circumvents the Windows Store -- the Microsoft-curated distribution channel for all Metro apps -- and when installed on the Windows 8 classic desktop, simultaneously installs the Metro version.
The biggest caveat for a Metro enabled desktop browser is that only the default browser -- which is set by the user -- can run in the Metro UI.
Like Windows 7, Windows 8 will initially assign IE as the default browser.
Mozilla's work began months ago, after last September's Build conference where Microsoft released the rough-edged Windows 8 Developer Preview. But programming was impossible until Microsoft provided documentation that described how to construct a crossbreed browser.
That documentation was published at the Feb. 29 launch of Windows 8 Consumer Preview, putting IE's rivals at a five-month disadvantage (download Word document). Bondy also said the whitepaper "lacked quite a bit of information" and that Mozilla developers had to fill in the gaps by hacking the Windows 8 registry.
Mozilla has only a rough timeline for Firefox on Windows 8. The proof-of-concept of Firefox for Metro is currently slated to ship alongside Firefox 14, which has a launch date of July 17. From there, Mozilla will work through its normal progression of alpha and beta versions before shipping final code.
Asa Dotzler, director of Firefox, said in a reply to questions that he does not expect Mozilla will ship a final version of a Metro style enabled Firefox in time to make the launch of Windows 8.
Microsoft has not yet disclosed a ship date for Windows 8, but most analysts anticipate the operating system will debut in the fourth quarter.
In a comment he posted last week on ZDNet's "The Ed Bott Report" blog, Dotzler was more specific about timing. "I do not anticipate that we will get beyond a late stage Beta this year," Dotzler said there.
Today, Dotzler confirmed that, "[This] is an accurate picture of our current thinking..., [but] that may change as we progress."
Google also said it would build a Metro-enabled version of its Chrome browser for Windows 8, but did not spell out a development timeline.
"Our goal is to be able to offer our users a speedy, simple, secure Chrome experience across all platforms, which includes both the desktop and Metro versions of Windows 8," a Google spokesman said yesterday. "To that end we're in the process of building a Metro version of Chrome along with improving desktop Chrome in Windows 8, such as adding enhanced touch support."
Norwegian browser maker Opera Software stopped just short of making the same promise.
"We can't comment on any specifics yet, other than [that] we are currently looking into Windows 8," said an Opera spokesman today. "The new OS and the Metro UI offers an interesting new platform and we know users will want to run Opera on it."
Apple does not comment on future products, but it's unlikely the Cupertino, Calif. company will rush to support Windows 8: Although Apple launched Safari for Windows nearly five years ago, almost all Safari users run it on Mac OS X.
Al Hilwa, an analyst with IDC, applauded Microsoft for letting other browser developers compete on Windows 8's Metro UI. But he acknowledged that it may have been motivated by antitrust concerns.
"Given the history of Microsoft's travails with DOJ and EU, it is smart for them to open up the browser environment," said Hilwa, referring to the scrutiny Microsoft has faced from regulators in the U.S. and the European Union. "[And] a higher level of openness may prove to be an important point of differentiation for Windows 8 compared to Apple's [iOS] platform."
In 2009, Microsoft agreed to offer a browser choice ballot in Windows XP, Vista and Windows 7 to European users after Opera complained to EU's antitrust commission that Microsoft was using Windows' dominance to shield Internet Explorer from competition.
The ballot offers users download links for other browsers.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed. His email address is email@example.com.