Google has released its "stable" version of Chrome 4.0, an incarnation under development for months that brings extensions to customize Chrome features and a host of technologies for more powerful Web programming.
However, the new version is available only for Windows. The Mac OS X and Linux versions of Chrome arrived in beta more than a year after the Windows version, and there's still catching up to do.
Though this release is called version 4.0, Google de-emphasizes such numbers, calling them mere "milestones" on the way to a better browser. The software updates itself by default, keeping people on the latest version.
Extensions are a major browser feature, letting people add new abilities without burdening all users who might not be interested. Extensions are a major competitive advantage of Mozilla's Firefox, which calls them add-ons and has thousands available for download.
Mozilla is moving to a new extensions foundation called Jetpack that, like Chrome's technology, uses Web standards such as HTML and CSS. Mozilla will support the current XUL system but hopes Jetpack will offer advantages of easier development, installation, and updates.
Programmers have been working on various extensions, and Google on Monday launched its extensions gallery with more than 1,500 available.
Extensions are on the way for non-Windows users.
"To those using Google Chrome on Linux, extensions are enabled on the beta channel," said Chrome Product Manager Nick Baum in a blog post. "And for those using Google Chrome for Mac, hang tight--we're working on bringing extensions, bookmark sync, and more to the beta soon."
Also in the new version is bookmark sync, which means a bookmark added once by Google account holders will see that bookmark in all instances of Chrome they use. Unlike Mozilla's Weave extension, though, it doesn't synchronize passwords or extensions.
He also continued to bang the browser performance drum, citing a 42 percent increase in Mozilla's Dromeao DOM Core Tests that measure, among other things, how fast a browser processes a Web document.
Under the covers is Chrome support for several HTML5 technologies: including the LocalStorage and Database interfaces for letting browser applications or Web sites store data on a computer, the WebSockets interface for more advanced communications between a computer and a server, and the notifications interface for status bar alerts--think Web-based instant-messaging notes.
For details on the interfaces, check the Chromium blog.