Blockchain Java Backend Developer

Core Backend Skills

• Strong proficiency in Java (8+)
• Experience with Spring Boot / Spring Cloud
• Experience building distributed systems and microservices architectures at scale
• Strong knowledge of: Concurrency, multithreading, asynchronous programming
• API design (REST/gRPC)
• Security (OAuth2/JWT)
• Integration patterns
• Solid understanding of data stores: SQL (PostgreSQL/MySQL) and/or NoSQL (MongoDB/Cassandra)
• Caching (Redis) and search (Elasticsearch) is a plus
• Hands-on experience with message streaming/queues

Blockchain Skills (Must-Have)

• Strong understanding of blockchain fundamentals: Transactions, blocks, confirmations/finality, consensus, gas/fees, wallets, keys
• Experience integrating backend services with blockchain networks/nodes: Ethereum-compatible networks (Ethereum/Polygon/BSC) using Web3j, ethers-style approaches and/or permissioned chains (Hyperledger Fabric, Corda, Quorum)
• Experience supporting large blockchain deployments: Node connectivity, RPC management, event indexing, chain reorg handling, retry strategies

DevOps / Cloud (Preferred)

• Experience with Docker and Kubernetes for containerized microservices deployments
• CI/CD exposure (Jenkins/GitHub Actions/GitLab CI/Azure DevOps)
• Cloud experience (Azure/AWS/GCP) is a plus
• Understanding of security practices: Secrets management (Vault/KMS), TLS, RBAC, network security

Design and Development

• Design and develop Java-based backend services that interact with blockchain networks and nodes (public or permissioned)
• Build and scale microservices-based architecture supporting blockchain transaction workflows, event processing, and off-chain components
• Develop reliable services for: Transaction orchestration, smart contract invocation, blockchain event subscription/listening, on-chain/off-chain data synchronization
• Implement scalable APIs (REST/gRPC) for blockchain-enabled products and integrations
• Optimize performance for high throughput and low latency: Transaction throughput handling, batching, retries, idempotency, rate limiting
• Ensure secure integration with blockchain: Key management best practices, signing transactions, secure secret handling
• Implement observability and reliability standards: Logging, monitoring, tracing, alerting, SLOs/SLAs
• Work with DevOps/SRE teams to support production deployments, incident triage, and capacity planning
• Contribute to architecture decisions including: Event-driven architecture (Kafka/RabbitMQ), caching strategies, database selection, and deployment topologies

Qualifications

• BACHELOR OF COMPUTER SCIENCE

Pay

$100,000-$130,000 a year