The open-source Web browser has gained one more percentage point in U.S. user share against Microsoft Corp.s IE browser during the past two months, reported WebSideStory Inc. on Tuesday.
As of the end of April, Firefox rose to 6.8 percent of browser usage, while IE dropped one percentage point to 88.9 percent, according to WebSideStory.
The Web analytics and digital marketing company, based in San Diego, Calif., tracks browser usage based on the percentage of unique browsers hitting its network of sites, which reach more than 30 million Internet users each day.
Since WebSideStory began tracking Firefox in November, the browser has more than doubled its user share, while IE has fallen below 90 percent for the first time in three years.
That slowdown could make it tougher for the Mozilla Foundation to meet its stated goal for 2005 of reaching 10 percent usage share in the United States, though Johnston said he expects Firefox to eventually reach that threshold.
"Its going to be pretty tight," Johnston said. "Instead of seeing a full percentage point every two months, were seeing it every three months.
"It seems like its a natural change as the early-adopter buzz is dying down. Its probably a healthy thing for Firefox, because it means that its not all buzz-driven but from a groundswell that its increasing."
Still, other usage surveys are showing that Firefox is making bigger gains on IE. In its April report on worldwide usage, OneStat.com found that Firefox held an 8.7 percent share, while IE had an 86.6 percent share.
A survey released last month by management consultant Janco Associates Inc. found that 10.3 percent of business professionals were using Firefox, compared to 83.1 percent for IE.
The Web browser market also could undergo more significant shifts starting this summer as both Microsoft and Mozilla are expected to release updates for their browsers.
Mozilla, of Mountain View, Calif., is working on Firefox 1.1, which was originally slated for a full release in June. Among its enhancements will be native browser support for the SVG (Scalable Vector Graphics) standard.
Meanwhile, Microsoft is planning to begin a beta test of IE 7 this summer. The Redmond, Wash.-based software maker has not pinned a date for a full release.
While IE 7 will mark the first time Microsoft has released a major browser since IE 6s 2001 release, Johnston said he doubts it will cause an immediate change in usage.
"I suspect the IE release will not change the market share numbers back, but will slow down the bleeding for IE," he said.
Mozilla also has battled four major security reports in three month, the most recent occurring this week when Mozilla acknowledged an extremely critical security hole that could let an attacker execute malicious code.
As for other Web browsers, they showed little shifting in WebSideStorys latest numbers. Netscape and non-Firefox Mozilla browsers accounted for 2.2 percent usage, while browsers such as Opera and Safari made up a 2.1 percent share.