Mozilla set an unofficial record for software downloads on the second day of Firefox 4's launch, the company said Friday.
In the 24 hours from early Wednesday to early Thursday, users downloaded 8.75 million copies of the new browser, an uptick from the 7.1 million logged by Firefox 4 its first day.
Last week's one-day tally broke the record established by Firefox 3.0 in mid-2008 when that browser was downloaded more than 8 million times within 24 hours. Then, Mozilla ran a "Download Day" campaign that resulted in a certified Guinness World Record .
Mozilla launched the final version of Firefox 4 around 6:30 a.m. PT Tuesday after more than a year of development.
Although Firefox 4's downloads bested Firefox 3's record, the achievement won't be official. In 2008, a Guinness representative monitored Mozilla's download servers to audit the number; no on-site official was present at Mozilla last week, a company spokeswoman said.
Firefox also thrashed Microsoft's Internet Explorer 9 (IE9) on the download count. Last week's 8.75 million for Firefox 4 was almost four times the 2.4 million Microsoft touted the week before as the 24-hour count for IE9 when it launched March 14 .
That didn't surprise one analyst, who cited pent-up demand for Firefox because of several months' worth of delays, and the difference between Firefox and IE9 users.
"The Firefox user base is primarily power user, with a much smaller percentage of corporate users compared with IE9," said Al Hilwa, an analyst with IDC. "Most large IE9 corporate users [work in] lock-downed environments, and so upgrading is under IT control and, thus, slower."
The advantage also goes to Firefox 4 because it runs on Windows XP, the 10-year-old operating system that IE9 has left behind. "Supporting XP will ultimately lead to improving share for Firefox 4 as HTML5 proliferates and users with XP machines want to participate in that," Hilwa said.
According to Web metrics company Net Applications, XP currently accounts for more than 61% of all copies of Windows in use.
Because of those advantages, Hilwa has high hopes for Firefox. "All indications are that Firefox 4 will end up being a blockbuster release for [Mozilla], helping them gain their mojo back at least for some time to come."
As of 3:30 p.m. ET Sunday, Mozilla's real-time scoreboard claimed that over 35 million copies of Firefox 4 had been downloaded since Tuesday.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer or subscribe to Gregg's RSS feed . His e-mail address is firstname.lastname@example.org .
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This story, "Firefox 4 sets unofficial download record" was originally published by Computerworld.