Mozilla Foundation consolidated financial statements, 2024

The audited consolidated statements for Mozilla Foundation and subsidiaries, years ended 31 December 2024 and 2023, audited by Hood & Strong LLP of San Francisco and available to be issued on 26 September 2025. Published beside the 2025/26 State of Mozilla. This is the first sourced claim this spoke has ever held about who pays for Gecko.

T1 — primary financial data, attested by an outside auditor, not the organization's own summary of itself. The narrative report published alongside it would be T3; this document is the ledger.

The numbers

All figures in thousands of US dollars, 2024 first, 2023 second.

What a royalty is, in Mozilla's own words

The revenue-recognition note says what the money is for:

"Mozilla provides the Firefox web browser, which is a free and open-source web browser initially developed by Mozilla Foundation and the Corporation. Mozilla incorporates search engines of its partners as a default status or an optional status available in the Firefox web browser. Mozilla generally receives royalties at a certain percentage of revenues earned by its partners through their search engines incorporated in the Firefox web browser."

So it is a revenue share on searches, not a flat fee for the default slot. Whatever firefox users are worth to the partner, Mozilla takes a cut of it. That matters for the spoke's economics question: the funding is indexed to how much searching Firefox users still do, which is the quantity statcounter-browser-share shows falling.

One customer

The concentration-of-risk note is the sentence the whole page is for. Its exact wording matters:

"Approximately 86% and 85% of Mozilla's revenues from customers with contracts were derived from one customer for the years ended December 31, 2024 and 2023, respectively. Receivables from that one customer represented 72% and 70% of the December 31, 2024 and 2023 outstanding receivables, respectively."

Two things to keep straight. The 86% is of revenue from customers with contracts — royalties plus subscription and advertising plus other revenue, $565.5M in 2024 — not of total revenue and support, which also carries $95.4M of investment income and $15.8M of contributions. So the one customer is roughly $486M, about 71% of everything that came in.

And the statements never name that customer. Not in the concentration note, not in the revenue note, not anywhere in thirty-five pages. That Google is the counterparty is well documented elsewhere; it is not documented here, and a wiki that cites this document should not pretend otherwise. What the audited record establishes is the shape of the dependency — one contract, most of the money — with the name supplied from outside it.

The engine costs less than the deal pays

Software development ran $290.4M in 2024, up 11.4% on 2023. That line covers all engineering, not Gecko alone, so it is a ceiling rather than an engine budget. Even as a ceiling it settles the arithmetic the spoke keeps asking about: the search deal brings in roughly $486M, and everything Mozilla builds costs $290M. Maintaining the last independent browser engine is affordable inside the payment from the dominant engine's vendor, with room to spare — and nothing here shows a second source that would cover it if the payment stopped. Investment income of $95.4M, up from $47.3M, is the nearest thing, and it is a fifth of the size.

Two more lines are worth naming because they undercut the reflex that Mozilla is a lean engineering shop under a large marketing budget: general and administrative was $163.5M and branding and marketing $86.3M, together $249.8M against $290.4M of software development. Expenses grew 18.4% while royalties grew 0.7%.

Housekeeping the notes disclose

• Foundation and Corporation are separate parties, and the trademark is priced. The Corporation paid the Foundation $22.6M in 2024 (2023: $18.4M) in license fees under a trademark license agreement, computed on the Corporation's annual royalty revenue. MZLA, which makes Thunderbird, paid $0.415M (2023: $0.267M).
• Subsequent events, after the balance-sheet date. In March 2025 an arbitrator awarded Mozilla part of what it claimed in the Mozilla Online matter, with the litigation unfinished and the gain or loss unknown. In April 2025 Mozilla shut down Fakespot and expects to book a $13.7M impairment on the acquired assets.

What this does not settle

The document is a ledger and answers ledger questions. It does not say what the search agreement's term is, whether it is exclusive, what happens to it under the US antitrust remedies against the counterparty, or how much of the $290.4M reaches Gecko as opposed to Firefox's product surface, mobile, or the services. Those need reporting or a court record, not this.

Related

mozilla · firefox · gecko · statcounter-browser-share · ladybird · falco-browser-engine · synthesis