Blockchain Developer

Key Responsibilities

• Design, develop, and deploy Web3 components and integrations for Citi's Digital Asset Platform, including smart contracts, on-chain event listeners, wallet integrations, and blockchain protocol connectors
• Build and maintain backend services that interface with public and permissioned blockchain networks (e.g., Ethereum, Hyperledger Besu, Corda, or equivalent)
• Develop, test, and audit smart contracts written in Solidity or equivalent languages, ensuring security, correctness, and gas efficiency
• Integrate Web3 libraries and SDKs (e.g., Web3J, Web3JS, Ethers.js, Viem) into enterprise Java and/or Node.js backend services
• Implement asynchronous, event-driven architectures to handle on-chain events, transaction lifecycle management, and blockchain state synchronization
• Collaborate with architects and senior engineers to contribute to the design of scalable, secure, and resilient Web3 infrastructure
• Support the integration of digital asset custody solutions, tokenization frameworks, and DeFi/TradFi bridging components
• Contribute to technical documentation, including smart contract specifications, integration guides, and architecture notes
• Stay current with the rapidly evolving Web3 ecosystem - tracking protocol upgrades, new token standards, Layer 2 solutions, and emerging tooling relevant to institutional use cases
• Work within Agile/Scrum frameworks, participating in sprint planning, stand-ups, and retrospectives within a distributed global team
• Help identify and resolve technical issues across the Web3 stack, escalating where appropriate to ensure delivery quality and timelines

Qualifications / Experience

• Bachelor's degree in Computer Science, Engineering, or a related discipline; MS is a plus
• 8+ years of overall software engineering experience, with a strong backend development foundation
• 2 to 4 years of hands-on experience in Web3 and blockchain application development, including smart contract development and blockchain protocol integration
• 3 to 5 years of experience with backend development using Java/Spring, Node.js, or equivalent enterprise frameworks
• Proficiency in Solidity smart contract development, including testing frameworks (Hardhat, Foundry, Truffle) and security best practices
• Solid understanding of blockchain fundamentals - consensus mechanisms, transaction lifecycle, gas models, wallet infrastructure, and key management
• Experience with token standards (ERC-20, ERC-721, ERC-1155, ERC-3525, or equivalent) and tokenization patterns
• Familiarity with permissioned blockchain networks (Hyperledger Besu, Fabric, Corda, or R3) is a strong plus
• Experience with asynchronous programming, event-driven systems, and message queuing (Kafka, RabbitMQ, or equivalent)
• Understanding of cryptographic concepts - digital signatures, hashing, PKI, and secure key management - as applied to blockchain systems
• Exposure to Layer 2 scaling solutions (Polygon, Optimism, zkSync, etc.) and cross-chain interoperability protocols is a plus
• Experience in financial services or regulated industries is a plus
• Familiarity with Agile/Scrum methodologies and distributed team collaboration tools