Senior Java Backend Engineer

Qualco Technology

Senior Java Backend Engineer at Quento Technologies delivering scalable backend services using modern Java and Spring Boot. Collaborating with teams on microservices and cloud-native applications.

Posted 5/4/2026full-timeAthens • 🇬🇷 GreeceSeniorWebsite

Tech Stack

Tools & technologies

ApacheAzureCloudDockerGRPCJavaJUnitKafkaKubernetesMicroservicesMockitoPostgresRedisSpringSpring BootSpringBoot

About the role

Key responsibilities & impact

Design and develop backend microservices using Java 21 and Spring Boot 3.x;
Build and maintain RESTful APIs with clear error handling and documented OpenAPI/Swagger specifications;
Implement gRPC services and clients, including Protobuf schema design;
Develop event-driven solutions using Apache Kafka consumers and producers;
Integrate backend services with external systems (OIC, Salesforce, SAP ISU);
Implement authentication and authorization using OAuth 2.0 / OIDC, including token validation and role-based access;
Write unit and integration tests using JUnit 5, Mockito, and Testcontainers;
Collaborate with DevOps teams on containerized deployments in Docker and Kubernetes;
Ensuring that all activities and duties are carried out in full compliance with regulatory requirements and supporting the continued implementation of the Group Anti-Bribery and Corruption Policy.

Requirements

What you’ll need

University degree in Computer Science, Engineering, or a related field;
3–5+ years of experience in backend development;
Strong hands-on experience with Java (preferably Java 21) and modern language features;
Proven experience with Spring Boot (microservices, REST controllers, data access layers, security);
Experience migrating applications from older Java versions (e.g., Java 11);
Solid knowledge of Kafka-based event-driven architectures;
Experience with PostgreSQL, Azure Cosmos DB, and Redis;
Good understanding of containerization (Docker) and Kubernetes fundamentals;
Strong understanding of backend security concepts (OAuth2, OIDC, RBAC);
Experience writing automated tests at unit and integration level;
Experience working in an Agile environment;
**Nice to Have**
Integration experience with Confluent Kafka or Azure Event Hubs;
Exposure to AKS environments;
Previous work with enterprise integrations (Salesforce, SAP ISU);
Familiarity with cloud-native observability tools;
Familiarity with Azure DevOps.

Benefits

Comp & perks

Competitive compensation, ticket restaurant card, and annual bonus programs
Cutting-edge IT equipment, mobile and data plan
Modern facilities, free coffee and beverages, indoor parking, and company bus
Private health insurance, onsite occupational doctor, and workplace counselor
Flexible working model, hybrid benefits & home equipment benefits
Onsite gym, wellness facilities, and ping pong room
Career and talent development tools
Mentoring, coaching, personalized annual learning and development plan
Employee referral bonus, regular wellbeing, ESG and volunteering activities

ATS Keywords

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Hard Skills & Tools

Java 21Spring Boot 3.xRESTful APIsgRPCApache KafkaOAuth 2.0OIDCJUnit 5MockitoTestcontainers

Soft Skills

collaborationproblem-solvingcommunicationadaptabilityattention to detail