{ "checked_at": "2026-09-14", "companies": [ [ "block", "Block · Bitkey & Proto", "Wallets & mining", "Block includes Bitkey, a Bitcoin self-custody wallet, and Proto, a Bitcoin mining product team.", "Hiring unconfirmed", "https://block.xyz/bitcoin", "https://block.xyz/careers/jobs", "B · Research", "The official board returned zero results at review. Dynamic-board availability is uncertain; no opening was verified." ], [ "fold", "Fold", "Payments & product", "Builds Bitcoin rewards and financial-app products, with an official company hiring board.", "No openings on board", "https://foldapp.com/", "https://ats.rippling.com/fold-inc/jobs", "B · Research", "The board linked from Fold’s website explicitly showed no open roles on 14 September 2026." ], [ "bull-bitcoin", "Bull Bitcoin", "Exchange & payments", "Provides a non-custodial Bitcoin exchange and OTC service, connecting Bitcoin purchases and spending.", "Hiring unconfirmed", "https://www.bullbitcoin.com/", "https://www.bullbitcoin.com/", "B · Research", "Product relevance confirmed from the company site; no specific engineering or design vacancy verified." ], [ "nunchuk", "Nunchuk", "Wallets & custody", "Builds multisig wallet, inheritance and developer tooling, including a CLI for policy-controlled wallet automation.", "Hiring unconfirmed", "https://nunchuk.io/", "https://nunchuk.io/developers", "B · Research", "The developer page is a product and integration route, not a job advertisement." ], [ "muun", "Muun", "Wallets & payments", "Develops a mobile self-custodial Bitcoin wallet supporting on-chain and Lightning payments, with recovery tooling.", "Hiring unconfirmed", "https://muun.com/", "https://muun.com/", "B · Research", "A team to study for mobile payment and recovery UX; no current vacancy verified." ], [ "ocean", "OCEAN", "Mining infrastructure", "Operates a Bitcoin mining pool and develops DATUM tooling for miner-controlled block templates.", "Hiring unconfirmed", "https://ocean.xyz/", "https://ocean.xyz/", "B · Research", "Mining and infrastructure relevance is confirmed; the team page is not evidence of an open role." ], [ "wizardsardine", "Wizardsardine", "Wallets & security services", "Builds Liana wallet infrastructure and offers Bitcoin protocol, architecture and code review services.", "Hiring unconfirmed", "https://wizardsardine.com/", "https://wizardsardine.com/", "B · Research", "Liana has an open-source contribution route. The company describes Revault as a prototype on hold. Services are not independently vetted." ], [ "anchorwatch", "AnchorWatch", "Custody infrastructure", "Builds Trident Bitcoin vault infrastructure and offers custody and insurance products for individuals and organizations.", "Hiring unconfirmed", "https://www.anchorwatch.com/", "https://www.anchorwatch.com/", "B · Research", "Product relevance confirmed; no developer or designer vacancy verified. Product geography does not establish employment eligibility." ] ], "resources": [ { "id": "fedimint", "name": "Fedimint technical reference", "category": "Build", "audience": "Rust & distributed-systems developers", "description": "Implementation documentation for Fedimint’s modular server and client crates, including wallet, ecash and Lightning components.", "try": "Trace one client operation through the relevant crates and draw the message flow, including a failed response.", "note": "Advanced material. Document the federation’s trust assumptions alongside the code.", "url": "https://docs.fedimint.org/", "checked_at": "2026-09-14" }, { "id": "cashu-dev-kit", "name": "Cashu Dev Kit", "category": "Build", "audience": "Ecash application developers", "description": "A Cashu implementation and documentation for building mint and wallet integrations around Bitcoin-backed ecash.", "try": "Create a local token-lifecycle diagram, then test one documented example with development data.", "note": "Ecash depends on the issuing mint; describe redemption and issuer trust explicitly.", "url": "https://cashudevkit.org/introduction/", "checked_at": "2026-09-14" }, { "id": "core-lightning", "name": "Core Lightning documentation", "category": "Build", "audience": "Lightning & plugin developers", "description": "Node setup, APIs, plugin development and contributor documentation for Core Lightning.", "try": "Build a small plugin in a local development environment and record its behavior when a dependency fails.", "note": "Use documentation matching your installed release and keep examples in a test environment.", "url": "https://docs.corelightning.org/docs/home", "checked_at": "2026-09-14" }, { "id": "lnd-builder-guide", "name": "LND Builder’s Guide", "category": "Build", "audience": "Lightning integration developers", "description": "Lightning Labs’ guide to LND, node configuration and its surrounding payment tools and APIs.", "try": "Map the permissions, invoice states and recovery steps needed by a small payment integration.", "note": "LND, Core Lightning and LDK have different integration models; choose documentation for the implementation you use.", "url": "https://docs.lightning.engineering/", "checked_at": "2026-09-14" }, { "id": "warnet", "name": "Warnet", "category": "Build", "audience": "Protocol testers & infrastructure engineers", "description": "A tool for constructing Bitcoin network topologies, running scenarios and inspecting node logs and performance.", "try": "Run a small local scenario, save the topology and versions, and explain one observed network behavior.", "note": "An advanced test lab. A local experiment is not a measurement of the public Bitcoin network.", "url": "https://github.com/bitcoin-dev-project/warnet", "checked_at": "2026-09-14" }, { "id": "nigiri", "name": "Nigiri", "category": "Build", "audience": "Wallet & integration developers", "description": "A Docker-based command-line environment for Bitcoin regtest, with optional Lightning, Liquid and Ark components.", "try": "Create and confirm a regtest transaction, then document a reproducible reset and rerun.", "note": "Requires Docker; the project recommends WSL for Windows. Development coins have no monetary value.", "url": "https://github.com/vulpemventures/nigiri", "checked_at": "2026-09-14" }, { "id": "liana", "name": "Liana wallet source & contribution guide", "category": "Contribute", "audience": "Rust developers & wallet designers", "description": "Open-source wallet code with immediate spending and timelocked recovery paths, a Rust daemon and graphical interface.", "try": "Follow the project’s Signet trial guide and document how the interface explains a recovery path becoming available.", "note": "Use the linked contribution and security policies. A demo is not a security audit or inheritance plan.", "url": "https://github.com/wizardsardine/liana", "checked_at": "2026-09-14" }, { "id": "stratum-v2", "name": "Stratum V2", "category": "Reference", "audience": "Mining software developers", "description": "Mining protocol specifications and implementation resources covering pool communication and job declaration.", "try": "Diagram the roles of a miner, pool and template provider, then inspect an implementation’s message handling.", "note": "Check the chosen implementation’s supported features and platforms; protocol support is not a revenue guarantee.", "url": "https://stratumprotocol.org/", "checked_at": "2026-09-14" }, { "id": "bitcoin-command-line", "name": "Learning Bitcoin from the Command Line", "category": "Learn", "audience": "Developers learning Bitcoin interfaces", "description": "Blockchain Commons’ course connects command-line Bitcoin work with scripts, timelocks, PSBTs and programming interfaces.", "try": "Complete one relevant chapter, record the software versions and explain any steps you had to adapt.", "note": "Examples span several tools and languages. Check the chapter’s environment assumptions before running commands.", "url": "https://github.com/BlockchainCommons/Learning-Bitcoin-from-the-Command-Line", "checked_at": "2026-09-14" }, { "id": "development-philosophy", "name": "Bitcoin Development Philosophy", "category": "Learn", "audience": "Contributors with Bitcoin fundamentals", "description": "Kalle and Linnéa Rosenbaum’s book examines Bitcoin design tradeoffs, adversarial thinking and open-source development.", "try": "Write a short decision note comparing two approaches through decentralization, privacy and reviewability.", "note": "Best read after learning the transaction lifecycle and basic Bitcoin concepts.", "url": "https://bitcoindevphilosophy.com/", "checked_at": "2026-09-14" }, { "id": "nunchuk-developers", "name": "Nunchuk developer CLI & policy model", "category": "Build", "audience": "Wallet automation & application designers", "description": "A developer entry point for wallet automation with spending policies, signing controls and an open-source CLI.", "try": "Prototype an approval screen with fictional inputs: within policy, above the limit and waiting for another signer.", "note": "The quickstart shows mainnet. Confirm a supported test setup before integration; a policy demo should use no real funds or private keys.", "url": "https://nunchuk.io/developers", "checked_at": "2026-09-14" } ], "roles_added": [], "existing_roles_checked_at": "2026-09-13", "funding_rechecked": false, "evidence_method": "Primary company sites, project-maintained documentation and repositories; live browser inspection of Block and Fold hiring boards.", "exclusions": [ "No new confirmed vacancy was found among the eight added teams. Do not convert company relevance into a hiring claim.", "Block search snippets advertised older positions, but the current board returned zero results; hiring remains unconfirmed.", "Fold’s official Rippling board explicitly showed no open roles.", "Neutronpay homepage returned 404 in this scan and was not added.", "An old Swan Greenhouse search result was not adequate evidence for a new selected developer or designer role.", "Wizardsardine marks Revault as a prototype on hold; it is not presented as an active learning recommendation." ], "supporting_sources": [ { "title": "Fold official website (footer links its hiring board)", "url": "https://foldapp.com/" }, { "title": "Fedimint project overview", "url": "https://fedimint.org/" }, { "title": "Cashu protocol overview", "url": "https://cashu.space/" }, { "title": "Nunchuk wallet overview", "url": "https://nunchuk.io/" } ] }