Netscape also released some of its features as extensions for Firefox, including the Site Mail Notifier and Friends' Activity Sidebar, the Digg Tracker, as well as Netstripe, the new default theme for Netscape 9. Like Netscape version 8.x, Navigator 9 was based upon the Mozilla Firefox, this time version 2.0, and should have had full support of all Firefox add-ons and plugins, some of which Netscape was providing. The user interface of the program was also updated, and the theme was also later released for use on Mozilla Firefox. However, starting with Netscape Navigator 9 beta 3, the integration was optional, and certain aspects of integration could be manually enabled or disabled, with integration being totally removed in Navigator 9.0rc1 as the portal relaunched as Propeller.

The Beta releases of Netscape Navigator 9 included enhanced newsfeed support and were more integrated with the Internet portal, including enhanced methods of discussion, submission and voting of Web pages. It was the last web browser of the Netscape series. On January 28, 2008, Netscape revised this date to March 1, 2008, and offered support for migration to Flock and Mozilla Firefox.

On December 28, 2007, Netscape developers announced that AOL would discontinue their web browser on February 1, 2008. After a release candidate, the final release was issued on October 15, 2007. The program's first beta was released on June 5, 2007, with the Beta 2 on July 12, and Beta 3 on August 16. Netscape Navigator 9 is based on Mozilla Firefox 2.0. It also saw the return of the classic Navigator name, which was previously used during Netscape's heyday between versions 1.0 and 4.08 in the 1990s. After AOL outsourced the development of Netscape Browser 8 to Mercurial Communications in 2004, Netscape Navigator 9 marked the first Netscape browser to be produced in-house since the Netscape 7 suite. It was the ninth major release of the Netscape line of browsers. Netscape Navigator 9 is a discontinued web browser that was produced by the Netscape Communications division of parent AOL, first announced on January 23, 2007.

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