Firefox 1.0 — The Open-Source Browser That Took On Internet Explorer

Firefox is the open-source web browser made by the non-profit Mozilla. The final release, Firefox 1.0, came out on 9 November 2004. That day the Mozilla Foundation announced worldwide availability for Windows, Mac OS X and Linux, as a free download from mozilla.org or on CD from the Mozilla Store, in more than a dozen languages.

Its source goes back to the browser code Netscape opened in 1998 (see Netscape opens its source and mozilla.org is born). The Mozilla Suite built from that code bundled mail and a newsreader and was heavy. According to Wikipedia, Dave Hyatt and Blake Ross, among others, cut a browser-only experimental branch out of it, released it as Phoenix in September 2002, renamed it Firebird, and on 9 February 2004 renamed it again to Firefox.

What 1.0 offered

The 1.0 press release said the preceding Preview Release had been downloaded by more than eight million people, and listed these features.

Mitchell Baker, president of the Mozilla Foundation, credited the milestone to the efforts of hundreds of volunteers and developers around the world. The web of the day was almost entirely Internet Explorer's, and Firefox arrived as a free challenger whose source was open.

A browser its users marketed

Firefox spread differently from earlier software. Wikipedia says its marketing hub, Spread Firefox, launched on 12 September 2004 together with the Preview Release.

The emblem of that effort was a newspaper ad. On 15 December 2004 the Mozilla Foundation announced a two-page ad in the next day's New York Times, listing the names of thousands of people worldwide who had given to a fundraising campaign to support the 1.0 launch. It was coordinated by Spread Firefox, the volunteer advocacy site with more than 50,000 registered members, and its design was led by the San Francisco designer Christopher Messina. The same announcement put downloads to date at more than 11 million.

On 19 October 2005 Mozilla announced that downloads had passed 100 million. Firefox 3, released on 17 June 2008, recorded more than eight million downloads on its first day and was recognised by Guinness World Records (according to Wikipedia).

Peak share, then Chrome

On StatCounter's worldwide desktop figures, Firefox peaked at 32.21% in November 2009. That month Internet Explorer had 56.57%, and Chrome, a little over a year old, 4.66%.

What changed the picture was Google Chrome, launched in September 2008. On the same StatCounter series Chrome first passed Firefox in November 2011, 25.69% to 25.23%. Mozilla responded. According to Wikipedia, Firefox 5 on 21 June 2011 began a "rapid release" cycle matching Chrome's short release schedule. On 14 November 2017 Mozilla shipped Firefox 57 under the name Firefox Quantum, with a heavily rebuilt engine, and described it as more than twice as fast as Firefox from six months earlier.

Share did not come back. On StatCounter's desktop figures Firefox stood at 14.95% in December 2016, 8.39% in December 2020 and 6.09% in September 2026. Counting all devices, including phones, it had 2.79% in September 2026.

Funded by search deals

Firefox is free, but its search box earns money. Already in 1.0 the start page carried a Google search box. Mozilla's financial statements explain that it gives search partners default or optional status in the browser and receives royalties at a percentage of the revenue those partners earn through Firefox.

The dependence is heavy. According to TechCrunch, in 2014, the last year of the Google deal, that agreement brought in US$323 million of Mozilla's US$330 million in total revenue. On 19 November 2014 Mozilla signed a five-year partnership with Yahoo and made Yahoo the default search in the United States. With the launch of Firefox Quantum in November 2017 it ended that deal and made Google the default again in the United States and Canada.

In the financial statements published with its 2024 annual report, Mozilla's royalties for 2023 were US$494.87 million of total revenue and support of US$653.01 million. About 85% of revenue from customers with contracts came from one customer, which the statements do not name.

Firefox in the antitrust case

The relationship became an issue in the search monopoly case brought by the US Justice Department and the states against Google. The government's brief to the appeals court in July 2026, citing the August 2024 liability ruling, says that under its agreement with Google, Mozilla must make Google the default on all Firefox search access points.

In the remedies ruling of 2 September 2025 the district court barred Google from exclusive contracts but still allowed it to pay for default placement, provided the payments are not conditioned on exclusivity and the agreements last one year or less. According to the Congressional Research Service, one reason the court gave for rejecting a broader payment ban was the harm it could do to the competitive prospects of smaller browser developers who depend on those payments.

For the wider story see the internet and web timeline; for the Netscape era, Netscape; and for the search side, Google Search.