PioGroup Software is a team of professionals passionate about building reliable digital products. We are looking for an experienced Senior Blockchain Engineer with strong production experience working with the Bitcoin protocol and Bitcoin wallet/custody infrastructure.
The main focus of the role is developing and maintaining Bitcoin wallet infrastructure, including UTXO management, transaction construction and signing, PSBT, SegWit, multi-signature flows, fee management, and transaction lifecycle handling.
For this position, hands-on production experience specifically with the Bitcoin protocol is essential. General blockchain or Web3 experience alone is not sufficient.
Requirements
- 3+ years of production experience with Bitcoin / BTC infrastructure.
- Hands-on experience with Bitcoin-based protocols, UTXO model, PSBT, and BIP standards.
- Strong experience with Java, Spring Boot, and SQL.
- Experience working with production wallet or custody infrastructure.
- Good understanding of TDD and/or BDD practices.
- Familiarity with Domain-Driven Design principles.
- Experience working in a monorepo environment with shared libraries and coordinated CI/CD pipelines.
- Professional written and spoken English.
- Proactive communication and ability to raise blockers, technical concerns, and cross-team dependencies.
Bitcoin Protocol Expertise
We expect strong practical knowledge of:
- PSBT and BIP-174.
- UTXO management and coin selection.
- SegWit transaction structures.
- Bitcoin script types and descriptor formats.
- HD wallets and derivation paths.
- BIP-48 and BIP-67.
- P2WSH and multi-signature transaction flows.
- PSBT combination, signing, and finalisation.
- Witness data and BIP-143.
- DER signature encoding, low-S enforcement, and sighash types.
- UTXO indexing and balance calculation.
- Address discovery, gap limits, change address allocation, and address reuse prevention.
Transaction Lifecycle & Fee Management
Production experience with:
- Mempool monitoring.
- Fee estimation and fee-rate prediction.
- RBF (Replace-By-Fee).
- CPFP (Child-Pays-For-Parent).
- Stuck transaction detection.
- Transaction replacement and rebroadcasting.
- Confirmation monitoring.
- Double-spend detection.
- UTXO consolidation during low-fee periods.
Candidates should also clearly understand the operational difference between a transaction being:
- Broadcast.
- Accepted into the mempool.
- Confirmed.
- Confirmed at depth N.
A strong understanding of Bitcoin probabilistic finality, dust limits, fee spikes during network congestion, and the behaviour of unconfirmed transactions is also required.
Responsibilities
- Develop and maintain Bitcoin wallet infrastructure.
- Manage UTXOs and wallet balances.
- Construct Bitcoin transactions.
- Work with PSBT and SegWit.
- Implement multi-signature transaction flows.
- Handle fee estimation and fee bumping using RBF and CPFP.
- Monitor mempool activity and transaction lifecycle.
- Implement deposit detection and address-level balance monitoring.
- Support wallet recovery and descriptor-based address discovery.
- Participate in technical design and architecture decisions.
- Collaborate with other engineering squads and shared platform components.
Nice to Have
- Experience with multiple blockchain protocols.
- Experience with institutional-grade custody or wallet platforms.
- Experience working with systems processing high volumes of Bitcoin transactions.
Important: we are specifically looking for candidates with documented commercial experience working with the Bitcoin protocol, including UTXO management, PSBT, SegWit, BIP standards, and the Bitcoin transaction lifecycle. Testnet-only, personal wallet, or exclusively Ethereum/Web3 experience will not be sufficient for this role.
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