Hybrid Backend Engineer

at IKNOWHOW SA

• Job title: Backend Engineer
• Job type: Full Time
• Experience level: Mid level, Senior
• Salary: Not specified
• Degree requirement: Bachelor's Degree
• Tech skills: Distributed Systems, Docker, GraphQL, GRPC, Java, Jenkins, JUnit, Kafka, Kubernetes, Microservices, Postgres, Pulsar, RabbitMQ, Spring, Spring Boot, SpringBoot, SQL
• Location requirements: Hybrid, Neo Psychiko, Greece

About the role

• Backend Engineer focusing on Java EE/Spring applications for defense-grade digital systems. Collaborating with cross-functional teams to develop secure, scalable backend services for mission-critical platforms.

Responsibilities

• Design, develop and maintain back-end of large web-based Java EE/Spring applications with microservices architecture.
• Write clean, maintainable, and testable code following industry best practices.
• Contribute to system design discussions and propose scalable, fault‑tolerant solutions.
• Improve system performance, reliability, and observability.
• Mentor junior and mid‑level engineers, perform code reviews, and guide best practices.
• Advocate for architectural improvements, performance optimizations, and engineering excellence.
• Participate in the technical analysis, documentation, implementation, and integration.
• Work closely with frontend engineers, DevOps, product managers, and QA to deliver end‑to‑end solutions.
• Build and optimize complex database schemas, queries, and stored procedures with PostgreSQL.
• Implement and maintain event‑driven architectures using messaging systems such as Kafka, RabbitMQ, or similar.
• Participate in API design (REST or GraphQL) and integration with external/internal services.

Requirements

• Bachelor's or Master's degree in Computer Science or other related field.
• 5+ years of experience building backend services in Java, using Java EE and/or Spring (Spring Boot/ Modulith).
• Solid experience designing and implementing backend microservices and modulith architectures, including service boundaries, inter-module communication, and dependency management.
• Hands‑on experience with event‑driven systems (Kafka, RabbitMQ, Pulsar, or similar).
• Strong expertise in SQL, database design, and performance tuning (preferably PostgreSQL).
• Experience developing and consuming REST APIs, with working knowledge of gRPC and GraphQL.
• Experience working with structured data formats, including JSON and XML.
• Experience integrating authentication and authorization solutions, ideally Keycloak, including OAuth2, OpenID Connect, and role-based access control.
• Basic to intermediate knowledge of CI/CD pipelines, with experience using tools such as Jenkins.
• Strong testing mindset (JUnit, integration testing frameworks).
• Expert-level experience with Docker, including container image creation, optimization, and security best practices.
• Hands-on experience deploying and operating containerized backend services on Kubernetes, including the use of Helm charts.
• Excellent problem‑solving skills and attention to detail.
• Strong communication and ability to collaborate in cross‑functional teams.
• Ownership mentality with a proactive approach to improving systems.
• **Νice to have:**
• Familiarity with secure backend development practices, especially for mission-critical or C2 systems, including secure communication, access control, auditing, and logging.
• Understanding of observability concepts such as centralized logging, metrics, and tracing in distributed systems.

Benefits

• Attractive salary package
• Comprehensive health insurance plan and additional benefits
• Career development and growth opportunities through a structured Job Grade System
• Continuous learning opportunities, including personalized training seminars and access to cutting-edge technologies
• Leadership role in a fast-growing company with a strong emphasis on innovation and technical excellence