Blockchain Java Backend Developer

New York City, NY / Jersey City, NJJob DescriptionBlockchain Java Backend DeveloperMust Have Technical/Functional SkillsCore Backend SkillsStrong proficiency in Java (8+), and frameworks such as Spring Boot / Spring Cloud.Experience building distributed systems and microservices architectures at scale.Strong Knowledge OfConcurrency, multithreading, asynchronous programmingAPI design (REST/gRPC), security (OAuth2/JWT), and integration patternsSolid Understanding Of Data StoresSQL (PostgreSQL/MySQL) and/or NoSQL (MongoDB/Cassandra)Caching (Redis) and search (Elasticsearch) is a plusHands-on Experience With Message Streaming/queuesBlockchain Skills (Must-Have)Strong Understanding Of Blockchain FundamentalsTransactions, blocks, confirmations/finality, consensus, gas/fees, wallets, keys.Experience Integrating Backend Services With Blockchain Networks/nodesEthereum-compatible networks (Ethereum/Polygon/BSC) using Web3j, ethers-style approaches and/or permissioned chains (Hyperledger Fabric, Corda, Quorum)Experience Supporting Large Blockchain DeploymentsNode 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/Google Cloud Platform) is a plus.Understanding Of Security PracticesSecrets management (Vault/KMS), TLS, RBAC, network security.Roles & ResponsibilitiesDesign 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 ForTransaction orchestrationSmart contract invocationBlockchain event subscription/listeningOn-chain/off-chain data synchronizationImplement scalable APIs (REST/gRPC) for blockchain-enabled products and integrations.Optimize Performance For High Throughput And Low LatencyTransaction throughput handling, batching, retries, idempotency, rate limiting.Ensure Secure Integration With BlockchainKey management best practices, signing transactions, secure secret handling.Implement Observability And Reliability StandardsLogging, monitoring, tracing, alerting, SLOs/SLAs.Work with DevOps/SRE teams to support production deployments, incident triage, and capacity planning.Contribute To Architecture Decisions IncludingEvent-driven architecture (Kafka/RabbitMQ), caching strategies, database selection, and deployment topologies.