A note posted on Mozilla's website suggests that a beta version of Firefox 2.0 could be released as early as today.
This much-anticipated release will be made no later than the end of this week, and no sooner than today, according to developer meeting minutes posted late last week.
Developers have been playing with an earlier alpha release of the browser since late March, but the beta release is expected to be tested by a much larger group of users. It marks a further step toward the final release of what is being billed as a major update to the browser.
A possible version of the beta, called a release candidate, has already been posted. That software can be downloaded here.
The latest version of the free browser is expected to include an "undo close tab" feature that lets users recover after they've accidentally shut a tab window. A spell checker designed to work with web forms is also in the works.
The update comes as Firefox is gaining market share on Microsoft's Internet Explorer.
Firefox is now used by nearly 13 percent of web surfers, according to analytics firm OneStat. That number is up 1.14 percent from May. In the US, Firefox has nearly 16 percent market share, but it is most popular in Germany, where it is used for nearly 40 percent of web visits.
Internet Explorer remains the dominant browser, however, with nearly 86 percent market share worldwide, according to OneStat.