Posted on 15 July 2021

Larry Ruane and Sebastian Falbesoner

Brink is proud to announce the recipients of its second round of open source developer grants. After an open grant application process, the Brink board of directors has selected two developers who have demonstrated continued commitment to open source Bitcoin protocol development. The grant recipients are:

Larry Ruane

Larry writes of his Bitcoin experience and goals:

I discovered the Bitcoin Core project through my full-time position at the Electric Coin Company, creators of Zcash, a code fork of Bitcoin Core. Upon discovering a small bug in Zcash in 2019, I found that the bug also existed in Bitcoin Core; the fix became my first PR. I immediately fell in love with the development community, and since then have been contributing review and a few small PRs on my own time, while continuing full-time with ECC. I was accepted to the 2020 Chaincode Residency program in New York, which was canceled, but I did participate in the Chaincode study group. My goal is to gradually move to working on Bitcoin Core full-time.

It’s well-known that Bitcoin Core is in crucial need of PR review, and this grant will allow me to spend one day of each week (20%) reviewing and testing PRs, while continuing 80% with ECC. I especially plan to take advantage of the weekly Bitcoin Core Review Club. I’ll work with community members to find which PRs would be most important and productive for me to help review. I may contribute some small PRs that arise from review. I have long-time experience with data storage system backend software, and the mindset there is one of absolute correctness – if data are ever corrupted or lost, there goes the system’s reputation. So I’ll be focusing on correctness, thread-safety, code organization and maintainability, test coverage, logging (for problem analysis), and related areas. I’m a big fan of the Unix philosophy’s emphasis on simplicity. (Tony Hoare said, “There are two ways to write code: so simple there are obviously no bugs in it, or so complex that there are no obvious bugs in it.”)

I’m very grateful to have been welcomed and mentored by many people in the Bitcoin Core developer community, and I’d like to especially thank John Newbery, Amiti Uttarwar, Adam Jonas, Gloria Zhao, and Dhruv Mehta.


Sebastian Falbesoner

Sebastian writes of his Bitcoin experience and goals:

Increasingly fascinated by the concept of a sound, digital form of money since reading about Bitcoin in 2014, I figured the best way to help the ecosystem, as a software engineer, would be by directly improving the reference implementation.

With some guidance from Jimmy Song’s introductory post, much reading of the docs, and diving deeply into the code, I opened my first pull request (#16753), which fixed a TODO concerning script parsing in the wallet code.

Many of my following PRs were focused on increasing test coverage in various areas (e.g. mempool acceptance policy, rejection causes of soft-forks like OP_CSV and OP_CLTV etc.), in addition to improving the performance of tests. I found that testing and code-reviewing PRs are very rewarding activities that open lots of learning opportunities and lead to new ideas on what to work on next. I also started participating in the PR review club, which is an excellent learning resource that I can warmly recommend to all interested in contributing.

Apart from fixing an inaccuracy in the BIP37 implementation, one of the most interesting topics I worked on last year was reverting a historic covert fix for a remote crash bug (CVE-2013-5700). As a personal highlight, the later PR also got covered in a PR review club meeting. This year I have also been working on making the ZMQ functional tests more robust and extending the test framework’s MiniWallet.

After more than 100 merged PRs, I am very excited about the future work that Brink’s support enables me to do; apart from ongoing thorough code review and testing, I plan to continue improving test coverage and extending the test framework, as well as improving the codebase, with a focus on the networking/P2P and wallet areas. Another plan is to deepen my understanding about the soon-to-be-activated Taproot/Schnorr soft-fork. In May 2020 I also started contributing to c-lightning, where I had the honor of naming release v0.9.0.


Both Larry and Sebastian will receive 6 month, part-time grants in order to secure their time to work on Bitcoin Core.

If you or your organization is interested in supporting open source Bitcoin development, feel free to email us,

Developers interested in either the grant or fellowship programs can apply now for the next funding round.

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