Executive warns Firefox risks future without Google search deal.

An executive from Mozilla warned on Friday that a potential ruling implementing the Department of Justice's proposed remedies in the Google antitrust case could threaten Firefox's very existence. "It’s very frightening," said Mozilla CFO Eric Muhlheim, referring to the possibility that the court could bar Google from paying to be the default search engine in third-party browsers like Firefox.

The DOJ's sweeping proposal includes forcing Google to sell its Chrome browser and mandating that it share search results with competitors. The court has already determined Google holds an illegal monopoly in search, partly due to exclusive deals that make it the default on browsers and phones, stifling competition. While Firefox directly competes with Chrome, Muhlheim testified that losing the substantial payments from its default-search deal with Google would endanger the browser's financial survival.

Firefox generates roughly 90 percent of Mozilla's revenue, according to Muhlheim, who leads finances for the organization's for-profit subsidiary. He added that approximately 85 percent of that browser revenue comes directly from the partnership with Google.

An abrupt loss of this income would force Mozilla to enact "significant cuts across the company," Muhlheim stated. He warned of a potential "downward spiral" if the company had to slash investments in Firefox's development, making the product less appealing to users. Such a spiral, he cautioned, could ultimately "put Firefox out of business," also jeopardizing funding for nonprofit initiatives like open-source web tools and AI-driven climate research.

Mozilla would have to make "significant cuts across the company"

Paradoxically, Muhlheim suggested this outcome could entrench the very market dominance the lawsuit aims to dismantle. He highlighted that Firefox's Gecko browser engine is "the only browser engine that is held not by Big Tech but by a nonprofit," contrasting it with Google's Chromium and Apple's WebKit. Mozilla originally developed Gecko to prevent a single entity, like Microsoft, from controlling internet protocols, thereby ensuring web interoperability and preventing corporate control of online access. (Unlike other trial participants, Firefox has not expressed interest in acquiring Chrome.)

Muhlheim explained that replacing Google's revenue is not a simple matter of striking a deal with another search provider or accepting a non-exclusive agreement with Google. Mozilla has explored the possibility with Microsoft's Bing, but he warned that without Google's competitive bids, the revenue share Mozilla could secure would likely drop. Furthermore, Bing currently does not monetize search traffic as effectively as Google.

A December 2024 presentation to Mozilla's board, shown in court, warned that losing Google's payments presented a "significant threat to viability for Mozilla with limited ability to mitigate." A 2021-2022 study, where some Firefox users were quietly switched from Google to Bing, found those users generated less revenue—a result Muhlheim said illustrates the financial risk of a full-scale switch.

Mozilla's past attempt to change default search engines was unsuccessful. From 2014 to 2017, making Yahoo the default led to significant user dissatisfaction, with many switching browsers entirely.

"We would be really struggling to stay alive"

In theory, successful DOJ remedies could foster more high-quality search competitors that might vie for Firefox's default spot and replace Google's payments. However, Muhlheim argued this process would take so long that Mozilla would be forced into drastic cuts and strategic shifts while "waiting on a hypothetical future." In the interim, he said, "we would be really struggling to stay alive."

Under cross-examination by the DOJ, Muhlheim acknowledged that relying on a single customer for most revenue is not ideal, regardless of the case's outcome. He also agreed that rival browser Opera earns more from browser ads than search deals. While this represents a potential diversification path for Firefox, Muhlheim noted scaling a similar ad business may be more challenging for Firefox, partly due to its strong commitment to user privacy.

The DOJ noted Mozilla supports choice screens for selecting a browser on phones and desktops—a feature from which it benefits. However, Mozilla does not support a mandatory choice screen for selecting a default search engine within a browser. Muhlheim testified that Firefox regularly reminds users of their search options, stating there are "a thousand different search points" in the browser. "Choice is a core value for us, but context matters," he added. "The best way to get to choice is not always a choice screen."

Judge Amit Mehta asked Muhlheim if Mozilla would benefit from having at least one other company matching Google's search quality and monetization ability. "If we were suddenly in that world," Muhlheim replied, "that would be a world that would be better for Mozilla."