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September 24, 2026

Senior Backend Developer (Java / .NET)

Senior • On-site

140 - 170 PLN/yr

Warsaw, Poland

Quick Facts

  • Role: Senior Backend Developer (Java / .NET)

Description

Design, develop, and maintain backend services and RESTful APIs using Java or .NET. Build scalable, reliable, high-performance backend solutions for client-facing applications, integrating services and data with relational and NoSQL databases.

Responsibilities

  • Design, develop, and maintain backend services and RESTful APIs using Java or .NET
  • Build scalable, reliable, and high-performance backend solutions for client-facing applications
  • Design data models and integrate services with relational and NoSQL databases
  • Collaborate with front-end developers to define API contracts and ensure seamless system integration
  • Develop and deploy applications in containerized environments using Docker, Kubernetes, or OpenShift
  • Apply secure coding standards and software engineering best practices
  • Create and maintain unit and integration tests
  • Integrate applications with CI/CD pipelines and automated deployment processes
  • Monitor and optimize application performance, scalability, and reliability
  • Troubleshoot technical and production issues and support their resolution
  • Participate in technical design discussions, sprint planning, code reviews, and other Agile activities

Requirements

  • 8+ years of professional backend software development experience
  • Strong commercial experience with Java or .NET
  • Hands-on experience with Spring Boot or .NET Core/modern .NET
  • Strong experience designing and developing REST APIs
  • Experience with Docker and container orchestration platforms such as Kubernetes or OpenShift
  • Good knowledge of SQL and relational databases, including data modeling and query optimization
  • Experience with automated testing, including unit and integration testing
  • Familiarity with CI/CD pipelines and modern software delivery practices
  • Strong understanding of object-oriented programming and software engineering principles
  • Ability to work effectively in cross-functional Agile development teams
  • Fluency in English (written and spoken)

Nice to have

  • Experience with event-driven or messaging architectures (e.g., Kafka or MQ)
  • Experience with cloud-native application development
  • Knowledge of NoSQL databases
  • Experience within financial services, fund administration, or transfer agency environments

Benefits

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

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