Mozilla Warns Firefox Could Shut Down if DOJ Wins Google Antitrust Case

The U.S. Department of Justice’s antitrust case against Google could have unintended and serious consequences for Firefox. As the trial continues, new testimony suggests Mozilla — the nonprofit behind the browser — may face a major financial blow if Google is barred from paying for default search placement.

Mozilla’s CFO, Eric Muhlheim, described the situation as “very frightening” during court testimony last Friday, according to *The Verge*. At the heart of the issue is the DOJ’s effort to stop Google from striking exclusive search deals — like the one that makes Google the default search engine in Firefox. The court has already concluded that Google maintains an illegal monopoly in part because of these types of arrangements.

For Mozilla, this isn’t just a legal speed bump — it’s an existential threat. Muhlheim revealed that Firefox generates about 90% of Mozilla’s overall revenue, and Google alone is responsible for roughly 85% of that. Losing those payments could force the organization to make deep cuts across the board, setting off a possible “downward spiral” that could drive users away and shrink revenue even more. According to Muhlheim, it could ultimately “put Firefox out of business.”

This is shaping up to be a case of well-intentioned regulation with unintended consequences. While the DOJ aims to open the search market to more competition, the proposed remedies might actually wipe out one of Chrome’s few remaining rivals. The numbers shared in court underscore what’s at stake. Firefox is built on the Gecko engine — one of just three major browser engines in use today — and notably, the only one not owned by tech giants like Google (Chromium) or Apple (WebKit).

Mozilla can’t easily pivot to a new search partner either. Muhlheim said the company has spoken to Microsoft about using Bing instead of Google, but without Google in the bidding war, any deal would be worth significantly less. Past experience doesn’t help either — Mozilla briefly switched to Yahoo as the default search engine from 2014 to 2017, but the results were poor, with users unhappy and quick to abandon Firefox altogether.

The DOJ argues that over time, its measures could create more viable competitors to Google Search. But Muhlheim cautioned that Mozilla might not last long enough to see that happen. “We would be really struggling to stay alive,” he testified. That leaves Mozilla caught in a paradox — financially reliant on the very company the government is trying to break up. A final ruling on the case’s remedies is still to come, but for Firefox users and advocates of a more open internet, the outlook is increasingly uncertain.

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