Blog Post: Fifteenth Wave of Bitcoin Grants

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+---
+title: "Fifteenth Wave of Bitcoin Grants"
+date: '2025-12-16'
+tags: ['OpenSats', 'grants', 'bitcoin', 'wave']
+authors: ['default', 'arvin']
+images: ['/static/images/blog/92-fifteenth-wave-of-bitcoin-grants.jpg']
+draft: false
+summary: "OpenSats is funding fifteen more open-source projects advancing the Bitcoin ecosystem."
+---
+
+We’re pleased to announce our latest wave of grants, supporting a mix of
+protocol research, core infrastructure maintenance, privacy-preserving wallets,
+and mining decentralization—work that benefits Bitcoin’s resilience as an open
+monetary network.
+
+This wave includes eight first-time grants and seven grant renewals. The
+projects and contributors in this round span different layers of the stack, from
+protocol-level work and Lightning infrastructure to operating systems, wallets,
+mining coordination, and Bitcoin Core maintenance. Together, they reflect a
+shared focus on strengthening Bitcoin as a public good by improving safety,
+decentralization, usability, and the ability for independent contributors to
+participate over the long term.
+
+The eight first-time grants in this wave go to:
+
+- [BlindBit Suite](#blindbit-suite)
+- [Dana Wallet](#dana-wallet)
+- [Daniel Pfeifer](#daniel-pfeifer)
+- [FreeBSD](#freebsd)
+- [Janb84](#janb84)
+- [LaWallet](#lawallet)
+- [LNHANCE](#lnhance)
+- [Mohd Zaid](#mohd-zaid)
+
+The seven grant renewals have been awarded to:
+
+- Bitcoin Dev Kit ([Aug. 2023](/blog/bitcoin-and-nostr-grants-august-2023#bdk))
+- Satoshi Nakamoto Institute ([Jul. 2024](/blog/announcing-the-opensats-education-initiative#satoshi-nakamoto-institute))
+- Africa Free Routing ([Sep. 2024](/blog/second-wave-of-education-grants#africa-free-routing))
+- Floresta ([Sep. 2024](/blog/bitcoin-grants-september-2024-7th-wave#floresta))
+- Yes Bitcoin Haiti ([Nov. 2024](/blog/3rd-wave-of-education-grants#yes-bitcoin-haiti))
+- Swift Bitcoin ([Jul. 2025](/blog/twelfth-wave-of-bitcoin-grants#swift-bitcoin))
+- Silent Payments Shepherd ([Aug. 2025](/blog/thirteenth-wave-of-bitcoin-grants#silent-payments-shepherd))
+
+These grants are made possible by donations to our [General
+Fund](/funds/general). If you’d like to help sustain free and open-source work,
+please consider donating:
+
+<center>
+  <DonateToGeneralFundButton />
+</center>
+
+Below, we take a closer look at each grant and the work being supported.
+
+---
+
+### BlindBit Suite
+
+BlindBit Suite is a collection of open-source tools focused on making Silent
+Payments practical and easy to use across different Bitcoin setups. The suite
+includes [BlindBit Oracle], an indexer that serves Silent Payments–specific data
+in a privacy-preserving way, and [BlindBit Desktop], a background wallet that
+continuously scans for incoming Silent Payments. [BlindBit Scan] is a
+lightweight, self-hostable service that keeps wallets up to date by querying
+Oracle. [BlindBit Spend] is a mobile wallet that connects to Scan to spend
+discovered UTXOs without doing on-device scanning. Together with supporting
+libraries, these components aim to reduce the heavy scanning burden that Silent
+Payments impose while preserving strong privacy for users and developers.
+
+With support from this grant, the project will focus on making each component
+stable and ready for regular use. BlindBit Desktop will move through alpha and
+beta testing toward a 1.0.0 release, while BlindBit Oracle will be optimized for
+higher performance and heavier loads, including work on faster sync and improved
+storage backends. BlindBit Scan will be prepared for a 1.0.0 release as a
+private scanner with easy self-hosting via Docker on platforms like [Umbrel] and
+[Start9]. BlindBit Spend will be cleaned up, tested, and prepared for wider
+distribution on Android and iOS. The project will also explore enhancements such
+as DM-style notifications between senders and receivers and GPU-accelerated
+scanning, with the goal of making Silent Payments adoption more accessible for
+both desktop and mobile users relying on remote scanners.
+
+Repositories: [blindbitbtc]  
+License: MIT
+
+[BlindBit Oracle]: https://github.com/setavenger/blindbit-oracle
+[BlindBit Desktop]: https://github.com/setavenger/blindbit-desktop
+[BlindBit Scan]: https://github.com/setavenger/blindbit-scan
+[BlindBit Spend]: https://github.com/setavenger/blindbit-spend
+[blindbitbtc]: https://github.com/blindbitbtc
+[Umbrel]: https://umbrel.com/
+[Start9]: https://start9.com/
+
+### Dana Wallet
+
+[Dana Wallet] is a mobile bitcoin wallet built for the donation use case and
+designed around [silent payments]. It does not offer receiving on legacy
+addresses, which removes the risk of accidental address reuse and helps protect
+user privacy. Incoming payments are discovered using a [BIP158]-like structure
+with local scanning, meaning no external server learns which addresses belong to
+the user. The wallet is also built around [BIP353] “email-like” payment
+identifiers, replacing copy-and-paste address flows with a more familiar and
+streamlined experience for donors and recipients.
+
+With support from this grant, Dana Wallet aims to move into a production-ready
+release, including a stable build on the Google Play Store. The work will focus
+on error handling, reliable recovery through chain rescans, and basic security
+features such as PIN or biometric protection. Beyond those core milestones, the
+project plans to improve the speed and consistency of scanning, allow users to
+register their own `username@danawallet.app` addresses, improve the
+transaction history view, and add features like offline mode and flexible
+denomination display. Over time, the project may introduce a contact list, and
+notifications between Dana Wallet users to make receiving silent payments more
+seamless.
+
+Repository: [cygnet3/danawallet]  
+License: MIT
+
+[Dana Wallet]: https://danawallet.app/
+[silent payments]: https://gist.github.com/RubenSomsen/c43b79517e7cb701ebf77eec6dbb46b8#file-silent_payments-md
+[BIP158]: https://github.com/bitcoin/bips/blob/master/bip-0158.mediawiki
+[BIP353]: https://github.com/bitcoin/bips/blob/master/bip-0353.mediawiki
+[cygnet3/danawallet]: https://github.com/cygnet3/danawallet
+
+### Daniel Pfeifer
+
+[Daniel Pfeifer] is focused on improving the long-term maintainability, safety,
+and clarity of the Bitcoin Core codebase. His work centers on cleaning up the
+build system by replacing ad-hoc scripts and undocumented conventions with
+declarative, reproducible [CMake] configurations, and on refactoring C++
+components so they are easier to understand and work on in isolation. This
+includes enforcing clear ownership rules in the code and removing unsafe
+constructs. He also aims to define, document, and promote modern [C++ coding
+guidelines] within the Bitcoin community, drawing on his involvement with the
+ISO C++ Committee, and to develop the [BtcK] multi-language API so that
+different programming languages can talk to Bitcoin Core through consistent,
+idiomatic bindings. Alongside this, Daniel prioritizes C++ education and
+mentorship by teaching fundamentals, sharing best practices, and helping new
+maintainers grow into long-term contributors.
+
+With support from this grant, Daniel will focus on concrete near-term milestones
+that support future architectural improvements. These include helping to prepare
+a stable C API for the [Bitcoin Kernel library], making sure its SDK is deployed
+cleanly with the correct headers, library artifacts, and package configuration,
+and replacing a patchwork of platform-specific packaging scripts with a unified
+CPack definition. Because improving maintainability and educating future
+developers is an ongoing effort, progress will be iterative and aimed at the
+long-term sustainability of the Bitcoin Core project.
+
+Repositories: [purpleKarrot/btck]; [bitcoin/bitcoin]  
+Licenses: MIT
+
+[Daniel Pfeifer]: https://github.com/purpleKarrot
+[CMake]: https://cmake.org/
+[C++ coding guidelines]: https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines
+[BtcK]: https://purplekarrot.github.io/btck/
+[Bitcoin Kernel library]: https://github.com/bitcoin/bitcoin/issues/27587
+[purpleKarrot/btck]: https://github.com/purpleKarrot/btck
+[bitcoin/bitcoin]: https://github.com/bitcoin/bitcoin
+
+### FreeBSD
+
+[FreeBSD] is an operating system used across servers, desktops, and embedded
+platforms, and is the most widely deployed of the [BSD family], second only to
+Linux among open-source operating systems. This project maintains the
+FreeBSD/EC2 platform, ensuring that FreeBSD runs reliably on [Amazon EC2] by
+producing and supporting cloud images and coordinating with the wider project.
+This work underpins operating system diversity for critical infrastructure,
+which is important for Bitcoin operators who cannot rely on a single-kernel
+monoculture.
+
+With support from this grant, [Colin Percival] will continue engineering work
+around the newly released [FreeBSD 15.0], including EC2 image builds and
+coordination needed to keep the release stable and supported. Additional work
+will extend to [future branches], addressing larger changes and issues deferred
+from 15.0 and improving the robustness and security of FreeBSD in cloud
+environments. The goal is to ensure that FreeBSD remains a well-maintained
+operating system option for long-term infrastructure, including those in the
+Bitcoin ecosystem that rely on operating system diversity to reduce systemic
+risk.
+
+Repository: [freebsd/freebsd-src]  
+License: BSD-2-Clause
+
+[FreeBSD]: https://www.freebsd.org/
+[BSD family]: https://ftp.netbsd.org/pub/NetBSD/NetBSD-current/src/share/misc/bsd-family-tree
+[Amazon EC2]: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/concepts.html
+[Colin Percival]: https://github.com/cperciva/
+[FreeBSD 15.0]: https://www.freebsd.org/releases/15.0R/announce/
+[future branches]: https://wiki.freebsd.org/Releng/16.0ISSUES
+[freebsd/freebsd-src]: https://github.com/freebsd/freebsd-src
+
+### Janb84
+
+[Janb84] contributes to Bitcoin Core with a focus on coordinating software
+release testing and improving the supporting documentation and feedback loop
+around that work. This includes maintaining Release Candidate Testing Guides and
+running dedicated feedback threads for testers, as well as facilitating group
+review and discussion of the testing process through the [PR Review Club].
+
+With support from this grant, janb84 will continue to expand his work on Bitcoin
+Core, including in-depth PR review and contributor-facing documentation such as
+[README]s and testing guides, with the goal of improving the quality of review
+and testing so changes are easier to evaluate and safer to release.
+
+Repository: [bitcoin/bitcoin]  
+License: MIT
+
+[Janb84]: https://github.com/janb84
+[PR Review Club]: https://bitcoincore.reviews/
+[README]: https://github.com/bitcoin/bitcoin/blob/master/doc/README.md
+[bitcoin/bitcoin]: https://github.com/bitcoin/bitcoin
+
+### LaWallet
+
+[LaWallet] is a Lightning wallet stack designed to make bitcoin onboarding
+simple and practical for communities. It provides Lightning Addresses,
+[BoltCards] for NFC payments, [Nostr Wallet Connect] as the backend, and can be
+deployed for free on platforms like [Vercel] or [Netlify] to give users an
+instant Lightning wallet experience. The same stack can run on self-hosted
+platforms such as Umbrel or Start9, where communities offer courtesy NWC
+accounts and guide users toward operating their own infrastructure. LaWallet’s
+core idea is progressive custody, where users can start with hosted providers
+and later move to their own node without changing their interface or habits.
+This model is already being deployed with [VEINTIUNO.LAT] across several
+circular economies.
+
+With support from this grant, LaWallet will focus on improving the stack through
+heavy testing, bug fixes, and completion of the admin dashboard. The project
+aims to have at least ten circular communities running the platform, improving
+the simple wallet frontend, NWC integrations, and BoltCard flows based on user
+feedback. Additional work will refine the deployment and management experience
+for operators, making it easier for grassroots initiatives to roll out Lightning
+Addresses, POS devices, and NFC cards while progressively guiding new users
+toward self-custody.
+
+Repository: [lawalletio/lawallet-nwc]  
+License: MIT
+
+[LaWallet]: https://lawallet.io/
+[BoltCards]: https://www.boltcard.org/
+[Nostr Wallet Connect]: https://nwc.dev/
+[Vercel]: https://vercel.com/
+[Netlify]: https://www.netlify.com/
+[VEINTIUNO.LAT]: https://veintiuno.lat/
+[lawalletio/lawallet-nwc]: https://github.com/lawalletio/lawallet-nwc
+
+### LNHANCE
+
+The LNHANCE Expedition project explores the proposed [LNhance soft fork] for
+Bitcoin by building and analyzing proof-of-concept implementations of [Eltoo]
+channels, hash-lock Ark ([hArk]), and [vaults], with a focus on
+OP_CHECKTEMPLATEVERIFY ([CTV]) and OP_CHECKSIGFROMSTACK ([CSFS]). Its goal is to
+understand the practical viability, limitations, and tradeoffs of these new
+opcodes in real-world channel, Ark, and vault designs. Current work centers on a
+CTV-only vault that uses a predefined spending plan to control how quickly funds
+can be moved, support a large number of deposits and withdrawals, and provide a
+secure recovery path with clear limitations for users, alongside tools,
+documentation, educational materials, and reusable libraries that help other
+developers adopt these designs.
+
+With support from this grant, the project will complete the CTV-only vault proof
+of concept, refine its command-line and minimal graphical interfaces, and
+document the CTV precomputed state machine design for both general and technical
+audiences. It will then implement Eltoo channels using CTV and CSFS in [LDK] and
+extend this work to multiparty Eltoo using a precomputed settlement state
+machine, comparing on-chain efficiency and design tradeoffs with existing
+approaches. Further work will apply CTV and CSFS to [Ark-like protocols] by
+implementing hArk in [bark] and exploring related designs such as [Erk]. The
+project will also simulate multiparty Eltoo coinpools as non-custodial payout
+mechanisms for decentralized miners such as
+([Braidpool](/blog/bitcoin-grants-feb-2024#braidpool)), and investigate
+additional vault designs, including social recovery, offline key delegation, and
+deleted key recursion aimed at reducing precomputation overhead to levels
+suitable for hardware wallets.
+
+Repositories: [LNHANCE-Expedition]  
+Licenses: CC0-1.0, CC BY 4.0, MIT
+
+[LNhance soft fork]: https://lnhance.org/
+[Eltoo]: https://bitcoinops.org/en/topics/eltoo/
+[hArk]: https://delvingbitcoin.org/t/evolving-the-ark-protocol-using-ctv-and-csfs/1602#p-4785-hark-hash-lock-ark-10
+[vaults]: https://bitcoinops.org/en/topics/vaults/
+[CTV]: https://bitcoinops.org/en/topics/op_checktemplateverify/
+[CSFS]: https://bitcoinops.org/en/topics/op_checksigfromstack/
+[LDK]: https://github.com/lightningdevkit
+[Ark-like protocols]: https://bitcoinops.org/en/topics/ark/
+[bark]: https://docs.rs/bark-wallet/latest/bark/
+[Erk]: https://blog.second.tech/erk-update/
+[LNHANCE-Expedition]: https://github.com/LNHANCE-Expedition
+
+### Mohd Zaid
+
+[Mohd Zaid] is a developer contributing to [Braidpool], zero-fee Bitcoin mining
+pool that aims to reduce centralization in the Bitcoin mining landscape.
+Braidpool replaces the single-operator model of traditional pools with a shared
+Directed Acyclic Graph ([DAG]) of “[beads]” (shares or weak blocks) that records
+miners’ work quickly and with less waste. Building on this braid-like structure,
+Mohd has been working on two core pieces of infrastructure: an [Audit Mode]
+proxy that transparently logs mining activity into the DAG to create a
+tamper-evident record of work performed, and an Unspent Hash Payout Output
+([UHPO]) module that serves as an auditable accounting layer for tracking what
+each miner is owed and how payouts are constructed.
+
+With support from this grant, Mohd will focus on turning these components into
+robust tools that miners and ecosystem partners can rely on. He will implement
+and strengthen Audit Mode, including the pass-through proxy, the DAG logic for
+anchoring mining events, and privacy features that let miners selectively share
+contribution data with contract counterparties. Mohd will then design and build
+out the UHPO module, defining its data model, core operations for tracking
+balances and settlement, and the logic to generate valid payout transactions. In
+the final phase, he plans to integrate Audit Mode and UHPO while researching and
+prototyping decentralized signing with [FROST] or similar threshold schemes,
+followed by comprehensive functional and integration testing. The goal is to
+provide an open-source foundation for transparent mining accounting and
+hashrate-linked financial tools, reducing dependence on centralized pool
+infrastructure.
+
+Repositories: [braidpool/braidpool]  
+License: AGPL-3.0
+
+[Mohd Zaid]: https://github.com/zaidmstrr
+[Braidpool]: https://github.com/braidpool/braidpool
+[DAG]: https://en.wikipedia.org/wiki/Directed_acyclic_graph
+[beads]: https://github.com/braidpool/braidpool/blob/main/docs/braid_consensus.md
+[Audit Mode]: https://github.com/braidpool/braidpool/pull/305
+[UHPO]: https://github.com/braidpool/braidpool/blob/main/docs/braidpool_spec.md#unspent-hasher-payment-output
+[FROST]: https://www.rfc-editor.org/rfc/rfc9591.html
+[braidpool/braidpool]: https://github.com/braidpool/braidpool
+
+---
+
+From Silent Payments tooling and donation-focused wallet UX to long-term Bitcoin
+Core maintainability, operating system diversity, and mining decentralization
+research, this fifteenth wave supports the kind of work that keeps Bitcoin
+robust and usable without sacrificing privacy or decentralization.
+
+By funding both new contributors and ongoing maintenance, we aim to reduce
+bottlenecks that would otherwise limit review capacity, user choice, and the
+ability for independent builders to participate over the long term.
+
+Our work is made possible by the generosity of our donors. If you’d like to help
+make the future of free and open-source Bitcoin development more sustainable,
+consider setting up a recurring donation to one of [our funds](/funds). Any
+amount helps.
+
+<div className="text-center">
+  <DonateRecurringButton />
+</div>
+
+If you’re building free and open-source Bitcoin software that advances
+decentralization, privacy, and user sovereignty, we encourage you to [apply for
+funding](/apply).