Today, more than 85 percent of Firefox users have at least one add-on installed; most of those, in fact, have an average of five add-ons, Mozilla says.

Among the most popular add-ons are AdBlock Plus, Firebug, NoScript, Personas Plus, and Video DownloadHelper, according to Jostedt. Privacy and security, search tools, bookmarks, and themes are among the most popular categories.

Also included in Mozilla's Add-Ons Gallery are more than 150,000 user-created collections of Firefox add-ons.

Automatic Update Success

Mozilla has plenty of reasons to celebrate its lately.