Five years in, the Bitcoin network continues to grow in importance and the open source contributors maintaining and hardening it continue to need long-term, stable support. In 2025, Brink funded eight engineers, supported two fuzz testing interns, completed Bitcoin Core’s first ever third-party security audit, and helped ship seven Bitcoin Core releases. We are proud to have played a role in that work.
Today we present Brink’s 2025 annual organizational and financial report.
We provide some highlights from our annual report below, with the full report available here.
This report focuses on organizational and financial reporting. For 2025, we detailed our engineers’ technical accomplishments in a separate 2025 Engineering Impact Report.
Fundraising
Brink’s donors contributed approximately $7,800,000 toward our mission last year. The continued generosity of our donor community, from individual contributors to institutional partners, makes it possible for Brink engineers to focus entirely on the long-term health of Bitcoin.
In the report, we list all of our major donors, who contributed over $5,000 each, and thank them for the crucial role they played in our success.
Expenses
In 2025, Brink’s total expenses were approximately $2,600,000, with approximately 87% directed to program activities. The summary of these expenses include:
- Programs: ($2,230,455)
- Developer salaries & grants ($1,749,927)
- Travel ($57,064)
- Office & research materials ($147,840)
- Broader Bitcoin Core infrastructure ($176,437)
- Bitcoin Core Developer meetings ($73,520)
- Bitcoin Optech ($25,667)
- General & Administrative Expenses ($314,028)
- Staff compensation ($246,718)
- Operational expenses ($67,310)
- Fundraising ($21,050)
We breakdown these items in more detail in the report.
Note: For clarity and transparency, all financial figures in this report are based on a cash accounting method for the 2025 calendar year. Audited, accrual-based financials will appear in Brink’s public 2025 IRS Form 990.
Organizational Highlights
While more details are available in the full report, we wanted to summarize some of the organizational initiatives that we are proud of.
Bitcoin Core’s First Security Audit
In 2025, Brink commissioned a third-party security audit of Bitcoin Core, conducted by Quarkslab. This was the first public external review of Bitcoin Core’s codebase by professional security researchers. The findings are documented in the full report.
Fuzzamoto
Brink engineer Niklas Gögge designed, built, and released Fuzzamoto, a new end-to-end fuzz testing framework for Bitcoin implementations. Fuzzamoto enables differential fuzzing across multiple Bitcoin implementations and raises the bar for network-wide security testing.
New Grant: Eugene Siegel
We were pleased to welcome Eugene Siegel as a new Brink grantee in 2025. Eugene has focused his work on Bitcoin Core’s P2P layer and network robustness.
Fuzz Testing Interns
In 2025, Brink launched an internship program focused on fuzz testing, hosting two interns: Dongjia Zhang and Stratos. Both interns contributed directly to Bitcoin Core’s testing infrastructure under the mentorship of Niklas Gögge.
Developer Visits to Brink
We continued to grow our developer visits program, bringing contributors from around the world to collaborate with Brink engineers in person. Brink covered travel and accommodations for these visits, which have proven to be a highly effective way to accelerate mentorship and cross-team collaboration.
Bitcoin Core Developer Meetings
In 2025, Brink staff helped fundraise and organize two Bitcoin Core “CoreDev Meetings” in Jamaica and Frankfurt, Germany. These gatherings remain essential for in-person collaboration among Bitcoin Core’s global contributor base.
Grant Committee
Niklas Gögge joined Brink’s Grant Committee in 2025, deepening the technical expertise informing our grant decisions and bringing additional perspective from a security-minded contributor.
Bitcoin Optech
Brink continued to support Bitcoin Optech in 2025, assisting with financial and administrative necessities. In 2025, Optech published 50 weekly newsletters totaling over 80,000 words of technical content, accompanied by over 60 hours of podcast with 75 unique guests. We are proud to help this independent community initiative continue to thrive.
Outlook
In 2026, Brink is focused on extending the programs that proved most valuable in our first five years including funding strong, experienced engineers, building out more testing capabilities, providing logistical and administrative support where it helps Bitcoin Core contributors do their work, and continuing our support of CoreDev meetings and Optech. We are also adding a few new initiatives including a bug bounty program, experimenting with enterprise testing software, determining how Brink can best participate in quantum efforts, and exploring integrating LLMs to augment productivity as well as software security.
To our donors and the engineers we fund: thank you for making this work possible.
Mike Schmidt
Executive Director
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