Senior Java Spring Boot Developer

Company Description

Estia Group is a future-driven fintech startup building a pioneering ecosystem of user-centric technologies. Born in Greece and built for the world, we design, operate, and scale real-world solutions that prioritize regulation, security, and seamless user experience. Our group operates across four pillars, Estia Tech, Estia Payments, Estia Exchange, and Estia Foundation working together to reshape the future of digital payments and smart living. At the heart of our innovation is Estia Payments, our upcoming digital payment platform designed to simplify how consumers and businesses manage everyday transactions.

At Estia, we don’t follow trends we build what comes next. We’re creating technology with real-world impact, and we’re always looking for talented people who want to be part of something bigger.

Role Description

We’re looking for a Senior Java Spring Boot Developer based in Greece or Cyprus, who thrives on solving complex backend challenges and is eager to shape system architecture in a high-growth fintech environment. You’ll design and implement robust backend services, guide technical decision-making, and contribute to a team that values clean code, scalable systems, and real-world problem solving.

This role is fully remote and reports directly to the CTO, collaborating closely with cross-functional teams.

What You’ll Do

• Design and develop backend systems using Java (10+) with Spring Boot, REST APIs, and Hexagonal Architecture.
• Lead and mentor engineering efforts on system design, architecture, scalability, and best practices.
• Build long-running synchronous/asynchronous workflows using decoupling, batching, and async execution patterns.
• Ensure fault tolerance, data consistency, concurrency control, and graceful degradation across distributed systems.
• Apply messaging patterns with Kafka: topics, queues, point-to-point, and pub-sub models.
• Implement idempotent consumers, retry strategies, dead-lettering, and event/message processing.
• Design resilient, versioned REST APIs that maintain backward compatibility and recover quickly from failures.
• Implement robust database strategies using PostgreSQL: ACID guarantees, indexing, isolation levels, and transactions.
• Utilize modern Java concurrency tools including virtual threads and traditional threading models.
• Participate in system modeling using DDD concepts, architectural diagrams (C4, sequence diagrams), and RFCs.
• Ensure observability through structured logging, metrics, tracing, and tools like OpenTelemetry, Prometheus, or ELK.

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• Apply secure coding principles (OAuth2, JWT, encryption, key management).
• Work with AWS cloud services (e.g., Lambda, ECS, SQS, Secrets Manager).
• Contribute to documentation, knowledge sharing, and continuous improvement of engineering practices.

Must-Have Qualifications

• 10+ years of hands-on Java backend experience building production systems.
• Strong proficiency with Java 20+, Spring Boot, and RESTful API design.
• Deep understanding of backend architectural patterns (Hexagonal, CQRS, event-driven patterns).
• Expertise with Kafka or equivalent messaging systems.
• Experience designing and operating distributed systems at scale.
• Strong understanding of concurrency, fault tolerance, and distributed transactions.
• Solid knowledge of PostgreSQL, schema design, performance optimization.
• Experience with AWS services and cloud-native application development.
• Familiarity with microservices, CI/CD (GitHub Actions), IaC principles.
• Strong understanding of API versioning, backward compatibility, and lifecycle management.
• Bachelor’s degree in Computer Science, Software Engineering, or related field, and a Master’s degree.

Nice-to-Have

• Experience in fintech, digital payments, banking, or regulated environments (PCI DSS, PSD2, AML/KYC).
• Familiarity with DDD (Domain-Driven Design).

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• Experience with observability tooling (Prometheus, Grafana, ELK, OpenTelemetry).
• Strong familiarity with JVM tuning, performance profiling, or high-throughput environments.
• Experience with testing strategies: contract tests, integration tests, event-driven tests.

Why Join Us?

• Work on mission-critical fintech systems with real-world, high-impact use cases.
• Be part of an ambitious team that values ownership, autonomy, and engineering excellence.
• Continuous training and professional development support.
• A culture that values diversity, inclusivity, and equal opportunity.
• Work in a company where your technical decisions shape the future of our payment ecosystem.

To Apply

Please submit the following as a single PDF:

• Cover letter explaining your motivation and why you are a strong fit.
• Résumé outlining your experience and achievements.

Applications are reviewed on a rolling basis until the position is filled.

While we appreciate all applications, we will contact only those selected for an interview.