Join Hack The Box (HTB) as a Senior Java Engineer, where you will be responsible for designing and implementing the microservices foundation at Hack The Box. Your mission involves applying architectural patterns, leading by example in creating robust Spring Boot services, and shaping foundational decisions around service boundaries, messaging, and data consistency. You will directly contribute to a platform where quality, security, and speed reinforce each other.

What You'll Do

Design and build new Spring Boot microservices, applying patterns that ensure consistency, resilience, and scalability.
Shape the API Gateway layer, enabling secure routing, composition, and cross-cutting concerns for our platform.
Collaborate with architects and teams to define service boundaries and integration strategies aligned with business needs.
Modernize legacy systems incrementally using strangler fig and anti-corruption layer patterns, no big bang rewrites.
Champion code quality through reviews, best practices, and hands-on guidance that elevates the entire team.
Partner with SRE, Platform, and QA to keep services observable, testable, and production-ready.
Contribute to architectural decisions, documenting trade-offs and communicating direction clearly.
Mentor fellow engineers, sharing knowledge on microservices, Spring ecosystem, and clean code practices.

What We're Looking For

Solid experience with Java and the Spring ecosystem (Spring Boot, Spring Cloud, Spring Data, Spring Security) in production environments.
Hands-on experience designing and building microservices, with practical knowledge of patterns like Saga, CQRS, Transactional Outbox, and API Gateway.
Strong understanding of distributed systems challenges—data consistency, service communication, resilience, and fault tolerance.
Experience with messaging systems (e.g., Kafka) and event-driven architectures.
Familiarity with containerization and orchestration (Docker, Kubernetes) and CI/CD pipelines.
Ability to communicate architectural decisions clearly, whether through diagrams, documentation, or conversations with technical and non-technical stakeholders.
A track record of mentoring or guiding other engineers—you don't just write great code, you help others do the same.

Technical Stack

Java, Kotlin, Spring ecosystem, API integration styles, Relational databases, noSQL, Docker, Kubernetes, Git, GitHub, Jira

Team & Environment

Team Size: A fully autonomous, high-performing team of senior engineers and architects.

Team Structure: Backend-oriented but T-shaped team. Operates with an agile mindset, taking ownership end-to-end. Collaborates closely with SRE/Infrastructure, Platform teams, QA, Data, Analytics, AI teams, Product teams, Product Owners, and Business stakeholders.

Reporting To: Senior Architects

Benefits & Compensation

Private insurance
25 annual leave days
Dedicated budget for training and professional development, participation in conferences
State-of-the-art equipment (Macbook, iPhone, and mobile plan)
Free lunch & snacks at the office
Full access to the Hack The Box lab offerings; so you can learn how to hack
Flexible/Hybrid working
Highly supportive and caring environment, fostering growth, flexibility, and autonomy
Exciting journey of continuous learning and problem-solving
Fun environment with global meet-ups

Work Mode

Type: hybrid
Locations: Greece
Flexibility: Fully Remote / Hybrid (2 days in the office, 3 days remote, plus one month of work from anywhere). For Greece: Candidates within 55 km of Athens office follow hybrid model. Candidates beyond that radius are fully remote.

At Hack The Box, we are committed to fostering a diverse, inclusive, and equitable workplace. We believe that diversity enriches our performance, services, and the communities we serve. As such, we ensure that all job applications are considered solely based on merit, skills, and qualifications. We do not discriminate on grounds of race, color, religion, gender, gender identity or expression, sexual orientation, national origin, genetics, disability, age, or veteran status. We are dedicated to providing a fair and respectful work environment that reflects our values.