Senior Software Engineer (Java)

IntellectEU; Northern (KY); Hybrid; USD 120,000 - 180,000; Part time

Benefits offered by this job

International offices

Professional development opportunities

Job summary

IntellectEU is hiring a Senior Software Engineer to lead backend development for wallet operations, asset transfers, and blockchain integrations in a highly regulated fintech environment. You will own the delivery of core services, implement secure communications, and drive event-driven workflows at scale.

The role is remote within the US, initially 3 months with possible prolongation. You will leverage Java and Spring Boot, API-first design, and microservices to build scalable, observable

Qualifications

• 7+ years building production-grade backend systems in regulated environments.
• Experience with blockchain networks, smart contracts, or tokenization platforms.
• Deep expertise in Java and Spring Boot.
• API-first design, RESTful contracts, and microservices architecture.
• Strong concurrent, multi-threaded, and asynchronous programming.
• Proven delivery of highly available, distributed applications.
• Experience with Apache Kafka and event-driven systems.
• Understanding of CI/CD, DevSecOps, and automated security controls.
• Experience with OpenTelemetry and distributed tracing.
• Ability to produce API specs and runbooks.

Responsibilities

• Own backend services delivery with fault tolerance, security, and scalability.
• Build API-first services integrating blockchain networks and internal systems.
• Implement secure service communications and zero-trust principles.
• Operate event-driven systems using Apache Kafka and asynchronous patterns.
• Create highly available, scalable, multi-threaded services.
• Integrate Web3 SDKs for on-chain interactions and signing.
• Instrument with logging, tracing, and observability tools.
• Maintain high test coverage in CI/CD pipelines.
• Produce API specs and operational runbooks.

Skills

Java

Spring Boot

RESTful API design

Concurrent programming

Distributed systems

CI/CD

Security controls

OpenTelemetry

APIs & microservices

Web3 libraries

Tools

Apache Kafka

Web3.js / Ethers.js

RESTful tooling

API specifications

Job description

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 give rising talent and industry veterans the space to explore, launch ideas, and collaborate closely with our clients. 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.

We are looking for a Senior Software Engineer to join a high-caliber Web3 engineering team of our client. This is a deeply technical,hands-on individual contributor role. The successful candidate will own the delivery of core backend servicessupporting wallet operations, asset transfers, transaction orchestration, blockchain integrations, andevent-driven workflows operating at scale within regulated financial environments.

Type of cooperation - b2b, 3-month initial contract with prolongation possibility. Location - US, remotely

Responsibilities

• 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.

Requirements

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.

We guarantee:

• 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.

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