Maelstrom — the family office of BitMEX co‑founder Arthur Hayes — has published the first annual report for its Bitcoin Grant Program, detailing how a small team of paid open‑source developers has strengthened Bitcoin’s privacy, security, and codebase resilience over the program’s first 20 months (which began in October 2024).
The report, authored by Grant Program Administrator Jonathan Bier, shows that five developers have been supported since inception and four remain active. Grants run on 12‑month contracts, paid monthly in Bitcoin, and can be stacked up to a cap of $400,000 per developer per year. Maelstrom fully funds the program; oversight is handled by a two‑person review committee: Arthur Hayes and Jonathan Bier.
Who’s building and what they’ve shipped
Two grantees are focused on Bitcoin Core — the node software that secures the network — and two concentrate exclusively on privacy primitives and tooling.
- Rkrux (grantee since Oct 2024)
- Emerged as one of Bitcoin Core’s most prolific reviewers: 1,155 review comments across more than 200 pull requests in 2025 (ranked 11th most active commenter on the codebase in a dashboard by developer Niklas Gögge), plus 400+ additional PR comments in the first five months of 2026.
- Work centers on MuSig2 (making multisig transactions appear like single‑sig on‑chain, improving privacy and reducing fees) and the transition from legacy wallets to descriptor‑based wallets to boost interoperability across the ecosystem.
- Stratospher (grantee since Nov 2025)
- Targets high‑risk areas: consensus‑critical validation and the peer‑to‑peer network.
- Discovered and fixed an undefined‑behavior bug in FindMostWorkChain, contributed to removing the BLOCK_FAILED_CHILD flag, and advanced DLEQ cryptographic proofs in libsecp256k1 related to Silent Payments.
- Presented on open‑source development and privacy at the Africa Bitcoin Conference, and emphasized that consensus bugs can split nodes — a failure mode without a clean recovery.
- Benalleng (grantee since June 2025)
- Full‑time on Payjoin, a transaction protocol where both sender and receiver add inputs, breaking the common-chain assumption that all transaction inputs belong to one party.
- Payjoin API has been integrated into Bull Bitcoin and Cake Wallet, with five or more additional wallet integrations underway; bindings released for Python, JavaScript, Dart, and C# to lower developer friction.
- Maelstrom highlights a key point: even minority Payjoin adoption reduces chain surveillance effectiveness network‑wide, benefiting users who don’t use the feature directly.
- Macgyver (grantee since June 2025)
- Focused on Silent Payments (Ruben Somsen’s 2022 proposal), which lets a recipient use a single static address to receive multiple payments without on‑chain reuse.
- Wallet support has progressed: Blindbit‑Desktop, Cake Wallet, and Dana Wallet now support both send and receive; Sparrow Wallet and Nunchuk have added send support.
- Bitcoin Core draft implementations exist for both phases but are on hold pending a Silent Payments module in libsecp256k1. Macgyver formalized the Silent Payments roadmap, produced BIP‑375 test vectors, proposed a BIP‑375 hardware signer implementation for Coldcard, and organized monthly working‑group meetups.
Why this matters
Maelstrom’s grants are intentionally narrow: they fund only open‑source Bitcoin protocol work, with no commercial conditions and no token incentives. Funding is paid in Bitcoin, the process is peer‑reviewed, and outputs are published in a transparent report. The team’s work — reviewing consensus code, hardening P2P privacy, and building transaction‑obfuscation tooling — rarely makes headlines but directly underpins the security and privacy of a network that holds hundreds of billions in value.
This report signals a notable approach to philanthropy in crypto: a private family office that profited from Bitcoin is reinvesting capital directly into the protocol’s core engineering, documenting the effort publicly. For an ecosystem that often rewards marketing and token launches, Maelstrom’s model — funding long‑term, technical open‑source work — is rare and could be influential if others follow.
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