According to Amsterdam-based OneStat, Firefox gained 2.8 percent usage share since April, while Microsoft's Internet Explorer, still the most widely-used browser, fell 1.2 percent over the same period. Internet Explorer now accounts for 85,5 percent of the world's browser share.
"The global usage share of Mozilla's browsers is still growing and it seems that Netscape users and some Internet Explorer users are switching to the Firefox version," said Niels Brinkman, co-founder of OneStat, in a statement.
OneStat's U.S. numbers look even better for the open-source Firefox. There, Firefox has 14 percent of the browser market, IE 80.7 percent, and Apple's Safari 3.6 percent.
Those numbers, and Brinkman's take on Firefox's growth, are at odds with those from U.S.-based Web measuring firms, which recently have seen Firefox's numbers slipping. A month ago, for example, Net Applications noted a three-quarter percentage point drop in the use of Firefox during September, and said the browser had been losing ground since June.
Part of the difference could be attributed to OneStat's habit of combining both Firefox and the browser in the Mozilla suite under the "Firefox" category; other measuring firms, including Net Applications, separates the two.
In earlier interviews, OneStat's Brinkman has also claimed a larger sampling size than U.S.-based rivals.