Developers working on Mozilla's next browser have added a privacy mode to the still-under-construction Firefox 3.1, a major milestone in the development of the upgrade.
The most recent test build of Firefox 3.1 adds what Mozilla calls "Private Browsing," said developer Ehsan Akhgari in a blog post on Tuesday morning. Akhgari has been the primary programmer working on the new feature.
In the blog, Akhgari outlined the mode's operation. He explained that it lets Firefox first memorise the current tabs so that it can reopen them at the end of the private-browsing session, and then slip a small notice at the top of the window to indicate that the next moves won't be recorded.
"After all, if you're doing something online that you don't want your co-workers to know about, you don't want to raise their attention with a big sign saying PRIVATE as they pass by and glance over your shoulder," said Akhgari.
As long as the mode is enabled, Firefox refuses to store traces of where the browser went and what it was asked to do. While in Private Browsing, Firefox will not record the browser history, search history, download history or form history, or save cookies or temporary files. Saved downloads and pages that are bookmarked, however, are not deleted.
Mozilla decided to include a privacy mode - sometimes dubbed "porn mode" as a sop to an obvious application - about eight weeks ago. The move was largely in response to competitive pressure from other browser makers, which were adding similar features to their software. Less than two weeks before Mozilla announced the privacy mode addition, for example, Google had released Chrome and touted its "Incognito" mode.
Internet Explorer 8 will also include a private-browsing feature, dubbed "InPrivate."
Originally, Mozilla officials were pessimistic about the chances of adding a privacy mode to Firefox 3.1, but several days after discussing the feature, the company decided to insert another four to five weeks of work to the schedule to make sure Private Browsing, and several other in-development pieces, made it into the final.
Tuesday, Akhgari said that the privacy mode would appear in Firefox 3.1 Beta 2, which will likely ship later this month. "This will be included in Firefox 3.1 Beta 2 which will be released soon, so if you want to try it, you can give it a shot then," he said. "And of course, it will appear in the final release of Firefox 3.1, so if you're not the type who test beta software, you can wait until Firefox 3.1 is released."
Users interested in trying out the privacy mode immediately, however, can download the pre-release version of Beta 2 - called "nightlies" by Mozilla - from the company's site.