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Liquidity.io · 1 month ago

Senior Blockchain Developer

United States

Full-time

Remote

Senior Level

5+ years exp

Liquidity.io is seeking an experienced Senior Blockchain Engineer with deep expertise in blockchain security and high-performance backend systems. The role focuses on building and securing institutional-grade blockchain protocols and decentralized applications, while also implementing secure key management systems and optimizing off-chain services.

BlockchainFinancial ServicesFinTech

Responsibilities

Design and implement secure key management systems using Hardware Security Modules (HSMs) (e.g., Thales, YubiHSM, AWS CloudHSM, Azure Dedicated HSM, or custom integrations)

Architect and develop production-grade blockchain nodes, smart contracts, and off-chain services on Substrate-based chains (Polkadot ecosystem, parachains, or standalone Substrate chains)

Build and optimize rollup infrastructure and smart contracts on Arbitrum (Arbitrum Orbit, AnyTrust, Nitro stack, Stylus, or custom chains)

Design, scale, and maintain high-throughput off-chain services and indexers using MongoDB as a primary data store for transaction metadata, user activity, analytics, and real-time state

Implement secure multi-party computation (MPC), threshold signatures (TSS), and HSM-backed key-generation ceremonies

Lead cryptographic protocol design and security audits for private key lifecycle management, wallet infrastructure, and staking/delegation systems

Integrate HSMs with blockchain runtimes and off-chain microservices for signing transactions, consensus messages, and cross-chain operations

Optimize MongoDB schemas, aggregation pipelines, and sharding strategies for blockchain event indexing and query performance at scale

Contribute to open-source Substrate frameworks, Arbitrum tooling, and internal MongoDB-based blockchain explorers/indexers when applicable

Perform threat modeling, security reviews, and incident response for both on-chain and off-chain systems

Qualification

Blockchain securityRust proficiencyMongoDB expertiseHardware Security ModulesSmart contract developmentCryptographic systemsArbitrum deploymentSoft skills

Required

5+ years of professional blockchain/smart-contract engineering experience

Production experience integrating and operating Hardware Security Modules (HSMs) in high-security environments (banking, custody, DeFi, or institutional staking)

Strong Rust proficiency with 2+ years building production Substrate pallets, FRAME runtimes, or custom Substrate-based chains

Hands-on experience deploying and maintaining Arbitrum-based chains (Orbit chains, Nitro nodes, fraud/proof systems, or Stylus contracts)

3+ years building and scaling production systems with MongoDB (complex aggregation frameworks, sharded clusters, change streams, replica sets, performance tuning)

Deep understanding of cryptographic primitives: ECDSA/secp256k1, EdDSA, BLS12-381, threshold signatures, and secure enclave/HSM workflows

Proven track record of shipping secure, audited blockchain systems and high-performance off-chain services used in production