Senior Software Engineer, Java

IntellectEU

Senior Software Engineer developing backend services for a fintech company with a focus on Web3 technologies. Responsible for delivery of core systems supporting wallet operations and blockchain integrations.

Posted 7/19/2026contractRemote • 🇵🇹 PortugalSeniorWebsite

Core Competencies

Role fit

Core Competencies

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Demonstrates extensive experience in building and operating production-grade backend systems with a focus on API-first design, microservices architecture, and event-driven solutions. Proficient in implementing secure service communications and operationalizing observability practices within regulated financial environments.

Highest-signal resume keywords

JavaSpring BootAPI-First DesignApache KafkaZero Trust Security Architecture

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Hard Skills

Backend Services ImplementationConcurrent ProgrammingAsynchronous ProcessingMicroservices ArchitectureAutomated Testing FrameworksDistributed ApplicationsMessaging PatternsOpenTelemetryTechnical DocumentationBlockchain Integration

Soft Skills

Technical Writing

Tools & Technologies

Web3 SDKsCI/CD PipelinesObservability PlatformsDistributed TracingCryptographic Signatures

Industry Keywords

Regulated Financial EnvironmentsDigital Asset OperationsTokenizationStablecoinsMulti-Party Computation

Tech Stack

Tools & technologies

ApacheJavaJavaScriptKafkaMicroservicesNode.jsSDLCSpringSpring BootSpringBootTypeScriptWeb3

About the role

Key responsibilities & impact

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

What you’ll need

7 or more years of software engineering experience building and operating production-grade backend systems in regulated financial or enterprise environments.
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.
Solid understanding of messaging patterns including pub/sub, event sourcing and saga/choreography orchestration.
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.
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.
Experience with AI-assisted development workflows and LLM-powered tooling.

Benefits

Comp & perks

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.
Work where you're most productive: remote, in-office, or hybrid options available.