Blockchain Developer

Role: Blockchain Developer

Location: New York, NY/Jersey City, NJ

Position Type: Full-time

10+ Years of experience

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

Participate in code reviews, providing and receiving constructive technical feedback to maintain high engineering standards

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

Hands-on experience with Web3 libraries such as Web3J, Web3JS, Ethers.js, or Viem

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)

Familiarity with DevOps practices, containerization (Docker, Kubernetes), and CI/CD pipelines

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

Competencies / Skills

Web3 Engineering Depth: Strong command of the Web3 technology stack - from smart contract development to on-chain/off-chain integration patterns and blockchain node interaction

Backend Engineering Fundamentals: Solid grounding in enterprise software engineering - API design, microservices, data structures, algorithms, and design patterns

Security Mindset: Awareness of common smart contract vulnerabilities (reentrancy, front-running, integer overflow, etc.) and best practices for secure on-chain development

Curiosity & Adaptability: Genuine enthusiasm for the Web3 ecosystem and the ability to rapidly learn and apply new protocols, standards, and tooling

Collaborative Spirit: Strong team player who communicates clearly and constructively with engineers, architects, and non-technical stakeholders

Delivery Orientation: Ability to manage personal delivery commitments, prioritize effectively, and produce high-quality output within sprint cycles

Attention to Detail: Rigorous approach to testing, code quality, and documentation - particularly important given the immutable nature of on-chain deployments

Tooling Proficiency: Working knowledge of engineering tools including Git, Jira, Jenkins, Hardhat/Foundry, Docker, Helm, and observability platforms