Blockchain Developer (Java)

Senior individual-contributor backend engineer responsible for designing, building, and operating production-grade, highly available, strongly consistent services for wallet operations, transaction orchestration, blockchain integrations, and event-driven workflows. Implement secure, scalable APIs, cryptographic key management, Kafka-based event systems, observability with OpenTelemetry, CI/CD pipelines, and produce tests, API specs, and operational runbooks. The summary above was generated by AI

IntellectEU is an international technology company focused on digital finance and emerging technologies. At IntellectEU we are on a mission to become the top-of-mind fintech company. We are committed to our people and believe in building a better future with the newest technologies. We give rising talent and industry veterans the space to explore, launch ideas, and collaborate closely with our clients. With our technical hands-on experience in payments, blockchain and capital markets, there’s no challenge that’s left unsolved. Over the past two decades, we have earned our expertise in financial technology, executing on hundreds of complex integrations and co-creating new digital asset platforms alongside our clients., * Implement and operationalize core backend services with fault tolerance, security, and scalability.

• Build API-first services integrating blockchain networks, third-party provider solutions, and internal systems with strong consistency guarantees.
• Implement secure service communications using cryptographic signatures, key management, and zero-trust architecture principles.
• Operationalize event-driven systems using Apache Kafka and asynchronous messaging patterns.
• Build highly available, strongly consistent, horizontally scalable services.
• Implement robust concurrent and asynchronous processing patterns for multi-threaded workloads.
• Integrate Web3 SDKs and libraries for on-chain interactions, transaction signing, and state monitoring.
• Implement structured logging, distributed tracing, metrics, and OpenTelemetry instrumentation.
• Produce and maintain high test coverage via automated unit, integration, and functional testing frameworks within CI/CD pipelines.
• Produce and maintain technical documentation, API specifications, and operational runbooks., Build and deliver backend enterprise web applications for Citi’s Integrated Digital Assets Platform using Java/Spring and web3 technologies. Collaborate with distributed teams, follow best practices and design patterns, write technical documentation, resolve issues, and ensure scalability, reliability, and performance. Top Skills: Asynchronous ProgrammingContainersGitHelm ChartsJavaJenkinsJIRASoliditySpringWeb3Web3JWeb3Js Photon, Design, develop, and maintain Java-based backend systems that integrate with blockchain platforms and smart contracts. Implement DApps and smart contracts, collaborate with cross-functional teams to deliver features, optimize performance and scalability, ensure secure blockchain interactions, and stay current with distributed ledger technologies. Top Skills: AWSAzureCi/CdDockerEthereumGCPHibernateHyperledgerJavaKubernetesMicroservicesNode.jsPythonRestful ApisSolanaSoliditySpring BootWeb3.Js CrowdStrike

Must Have:

• 7 or more years of software engineering experience building and operating production-grade backend systems in regulated financial or enterprise environments.
• Experience with blockchain networks, smart contracts, consensus mechanisms, crypto integration, or tokenization platforms.
• Extensive hands-on proficiency in Java and Spring Boot. Comfort operating across polyglot stacks.
• Deep expertise in API-first design, RESTful service contracts, and microservices architecture patterns.
• Strong command of concurrent, multi-threaded, and asynchronous programming models.
• Proven track record delivering highly available, strongly consistent, and distributed applications.
• Hands-on experience building event-driven solutions using Apache Kafka.
• Strong understanding of CI/CD, DevSecOps practices, secure SDLC, and automated security controls.
• Hands-on experience with OpenTelemetry, distributed tracing, and observability platforms.
• Strong technical writing skills; demonstrated ability to produce API specs and runbooks.
• Proven experience using Web3 libraries and SDKs (Web3.js, Ethers.js, or equivalent).

Nice to Have:

• Extensive hands-on proficiency in TypeScript, Node.js, and/or NestJS.

• Direct experience with Ethereum, Bitcoin, Solana, XRPL, and other distributed ledger technologies.

• Familiarity with MPC (Multi-Party Computation), HSMs, and enterprise key management systems.
• Experience implementing Zero Trust security architecture end-to-end.
• Knowledge of tokenization, stablecoins, settlement systems, and digital asset operations.
• Contributions to open-source blockchain projects or Web3 tooling.

115K-160K Annually Senior level 115K-160K Annually Senior level Cloud * Computer Vision * Information Technology * Sales * Security * Cybersecurity The role involves deploying and supporting CrowdStrike’s AI capabilities in cybersecurity, optimizing threat detection, and mentoring teams on AI solutions. Top Skills: AIAWSAzureBashChefCitrixGCPGroup PolicyIbm BigfixLinuxmacOSMachine LearningMcafee EpoPdqPowershellPuppetPythonRSccmSplunkSQLWindows

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• International experience in a stable company: the company has offices in Antwerp, Leuven, Lisbon, Krakow, Kyiv, New York and operates on the market for over 15 years.
• Passionate team in an innovative casual, positive, and open work environment ready to meet your new ideas.
• Great opportunities for personal and professional development as well as the chance to change the way the business works in the financial world.