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DCG Sp. z o. o. Logo DCG Sp. z o. o. · IT - Software Development

Principal Java Developer

Poland · Job Posted January 14, 2026
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Job Description

As a recruitment company, DCG understands that every business is powered by experienced professionals. Our management style and partnership approach enable us to meet your needs and provide continuous support. Due to our ongoing growth and the large number of recruitment projects we undertake for our partners, we are currently looking for: Principal Java Developer

Job Responsibility

  • Lead end-to-end development with Java (Quarkus/Spring) backend and React/TypeScript frontend, ensuring architectural consistency
  • Drive adoption of AI-assisted tools like Claude Code, guide prompt engineering, review AI-generated code, and integrate AI securely
  • Architect and implement scalable Java microservices and APIs with maintainable, testable code
  • Design and optimize MongoDB and PostgreSQL databases including schema, indexing, data modeling, queries, and migrations
  • Build event-driven systems with Kafka, implement event sourcing, reliable messaging, and integrate with ELK monitoring
  • Identify and resolve performance bottlenecks across frontend, backend, and databases, applying monitoring and optimization strategies
  • Maintain CI/CD pipelines in Jenkins, integrate SonarQube, Snyk, OWASP, manage Nexus repositories, automate deployments, IaC, and container orchestration
  • Define comprehensive testing strategies: unit, integration, end-to-end, performance, and security testing
  • Ensure full-stack security: secure coding, authentication/authorization, vulnerability and secrets management, compliance
  • Provide technical leadership, mentorship, code reviews, set standards, and make key architectural decisions
  • Integrate AI/ML services, LLM APIs, and intelligent automation, applying responsible AI practices
  • Collaborate with product, architecture, security, and business teams to translate requirements into technical solutions
  • Take full ownership of features and systems from design to deployment and maintenance

Requirements

  • 10+ years in software development, including 3–5 years in senior/principal roles with technical leadership
  • 8+ years Java (Quarkus/Spring Boot) with Maven/Gradle, JVM internals, performance tuning, and scalable enterprise apps
  • Full-stack expertise with React, TypeScript/JavaScript (ES6+), HTML5, CSS3, responsive design, Redux/Context API, and frontend optimization
  • Advanced MongoDB and PostgreSQL skills, including queries, indexing, replication, sharding, migrations, and data modeling
  • Experience with Kafka event-driven architectures and monitoring tools (ELK, Prometheus, Grafana)
  • DevOps and CI/CD skills with Docker, Kubernetes, Jenkins, SonarQube, Nexus, GitOps, Terraform/Ansible, and container orchestration
  • Experience with AI-assisted development (Claude Code, GitHub Copilot), LLM APIs, prompt engineering, and AI/ML frameworks
  • Strong testing skills: JUnit, Mockito, Testcontainers, Jest, React Testing Library, Selenium/Cypress, JMeter, Gatling
  • Security expertise: secure coding, OAuth2/JWT/OIDC, vulnerability management, and compliance
  • Performance engineering with profiling tools (JProfiler, VisualVM, Chrome DevTools) and APMs (New Relic, Dynatrace, AppDynamics)
  • Agile/Scrum experience, mentoring, technical decision-making, and process improvement
  • Strong communication, collaboration, and end-to-end ownership of initiatives
  • Passion for emerging technologies, AI-assisted development, and innovation

Nice to have

  • Experience with additional frontend frameworks (Vue.js, Angular)
  • Knowledge of GraphQL and API design patterns
  • Familiarity with observability platforms and distributed tracing
  • Experience in the aviation or air traffic management domain
  • Understanding of AIXM (Aeronautical Information Exchange Model) or aeronautical data standards
  • Contributions to open-source projects or technical community engagement
  • Certifications in relevant technologies (AWS, Kubernetes, Java, etc.)

What we offer

  • Private medical care
  • Co-financing for the sports card
  • Constant support of dedicated consultant
  • Employee referral program
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