As the U.S. Department of Justice (DOJ) advances proposals to rein in Google’s dominance in the online search market, one of the unintended consequences could be the destabilization of Mozilla Firefox—a long-standing independent alternative in the web browser space.
Mozilla, which relies heavily on Google funding to support its open-source Firefox browser, has issued a warning that the proposed antitrust remedies could inadvertently jeopardize the very diversity and competition regulators seek to protect, The Verge reported.
The concerns were laid out in federal court last week by Mozilla’s Chief Financial Officer Eric Muhlheim, who testified in defense of Google during the remedies phase of the DOJ’s landmark search monopolization case. Mozilla’s testimony sheds light on the fragile economics that underpin independent browser development and highlights a broader risk to the open web ecosystem.
Mozilla’s Financial Dependency on Google
At the heart of Mozilla’s concerns is its longstanding search partnership with Google. Muhlheim testified that approximately 85% of Mozilla’s revenue is derived from Google, with Firefox’s default search placement generating $495 million out of $653 million in total revenue in 2023.
“Losing that revenue all at once would mean Mozilla would have to make significant cuts across the company,” Muhlheim stated, warning of a potential “downward spiral” in which reduced engineering investment could lead to lower product quality, shrinking user numbers, and ultimately, Firefox’s collapse.
This dependency underscores a paradox in the DOJ’s case: while the agency seeks to prohibit default search deals that reinforce Google’s market power, doing so could devastate the few viable alternatives that provide consumers with meaningful choice in browsers and search engines.
Search Remedies and the Risk to Browser Diversity
The DOJ has argued that Google’s deals with browser vendors and device manufacturers unfairly suppress competition. One proposed remedy is to bar Google from paying for default search placement in third-party browsers, including Firefox.
Mozilla counters that such a remedy, though well-intentioned, could severely weaken browser competition. Its Firefox browser is powered by Gecko, the last remaining independent browser engine competing with Google’s Chromium and Apple’s WebKit. The removal of financial support from Google could threaten the viability of Gecko, Mozilla argues, leaving the web’s foundational technology in the hands of a duopoly.
“Banning default search placement deals may weaken Google’s grip, but it risks crippling the very alternatives meant to provide choice,” said Sanchit Vir Gogia, CEO of Greyhound Research. He urged regulators to differentiate between dominant platforms and smaller, dependent players.
Mozilla’s Experience With Alternatives
Mozilla has previously explored partnerships beyond Google. Between 2014 and 2017, Firefox adopted Yahoo as its default search engine in the U.S.—a move that proved unpopular with users and led to a measurable decline in market share.
Mozilla also evaluated Microsoft Bing as an alternative, but internal board presentations shown in court revealed that without competitive bidding, the value of such a deal would fall dramatically. “We found that people disliked the experience so much that they switched to another browser altogether,” Mozilla wrote in a recent blog post.
While the DOJ asserts that its proposed remedies will ultimately enable new search competitors to emerge, Mozilla argues that the transition period would be too long and too uncertain to sustain its operations in the interim.
A Difficult Pivot in a Privacy-Conscious Model
Under cross-examination, Muhlheim acknowledged the risks of overreliance on a single partner. Other browser companies, such as Opera, have diversified revenue through advertising. However, Firefox’s privacy-centric approach limits its ability to pursue similar monetization strategies.
Mozilla has started to expand into artificial intelligence tools and digital advertising, and recent changes to Firefox’s terms of use suggest the organization may be exploring new ways to balance revenue with its user-first principles. Nevertheless, such changes take time and investment—both of which are threatened if funding collapses.
Beyond Firefox: What’s at Stake for the Open Web
The broader implications of Mozilla’s warnings extend beyond its financial health. If Firefox were to disappear, it would not only eliminate a popular browser but also silence one of the few remaining independent voices in web standards development. Gecko’s demise would leave Google and Apple to shape the future of browser technology with little resistance.
“If Firefox were to shut down, it wouldn’t just mark the death of a browser — it would mark the end of one of the last surviving independent rendering engines,” said Gogia. Without such competition, innovation and user-centric development risk being subordinated to commercial priorities.
Mozilla CEO Laura Chambers echoed this in a public statement:
“This case will shape the competitive landscape of the internet for years to come, and any remedy must strengthen, rather than weaken, the independent alternatives that people rely on for privacy, innovation, and choice.”
A Delicate Balance for Regulators
Mozilla insists that it supports the DOJ’s goal of promoting search competition but urges the court to avoid trade-offs that could entrench existing browser monopolies. “Truly improving competition and choice cannot solve one problem by creating another,” the company stated.
Chambers emphasized that Mozilla’s mission-driven structure makes it distinct among browser vendors, offering a nonprofit-backed, privacy-respecting alternative in a market increasingly shaped by platforms with vertically integrated ecosystems.
As the court prepares to finalize its remedies in U.S. v. Google, Mozilla’s testimony serves as a reminder of the ecosystem-wide consequences that follow from disrupting long-standing market arrangements. Whether the court can craft a remedy that disrupts Google’s dominance without sacrificing the last of the independent browsers may prove a defining challenge in this historic antitrust case.
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