Senior Software Developer (Java Application Developer) (m/f/d)

Our brand Deutsche Telekom IT Solutions Slovakia entered the life of Košice region in 2006 under the name of T-Systems Slovakia and ever since has been inextricably linked with the region when became one of the founding members of Košice IT Valley. We have managed to grow from scratch to the second largest employer in the eastern part of the country with more than 3900 employees. Our goal is to proactively find new ways to improve and continuously transform into the type of company providing innovative information and communication technology services.

PURPOSE

Develops new and maintains existing applications using modern technologies (primarily Java) based on requirements of internal or external customers. These applications support automation and transformation of business-critical processes within the Telekom domain.

Works independently or as part of a project team on designing, developing, and building mid-size to complex, scalable applications in a cloud-native, microservices-based environment.

As part of the role, actively contributes to the migration of business logic from a legacy billing system (one of the top 100 most critical Telekom applications) into a modern streaming platform built on Quarkus and Kafka, designed to process millions of events daily.

TEAM AND PROJECT DESCRIPTION

As part of a team of experienced senior developers, you will contribute to our initiative focused on migrating business logic from a legacy billing system, currently one of the top 100 most critical Telekom applications into a modern Quarkus-based streaming platform.

The new solution is built on a microservice architecture, with services communicating via Kafka, and is designed to process millions of events daily. This transformation plays a key role in modernizing core Telekom systems and improving scalability and performance.

WHAT WILL YOU DO?
 

• Collaborate with stakeholders (business, product, architects) to understand requirements and translate them into scalable technical solutions
• Design and develop backend applications and microservices in a cloud-native environment
• Contribute to the migration of business logic from a legacy billing system into a modern event-driven architecture (Quarkus + Kafka)
• Design and implement REST APIs and event-driven communication between services
• Analyze requirements and propose robust, maintainable architecture solutions with focus on scalability and performance
• Estimate development effort, plan implementation, and support delivery planning
• Develop high-quality, clean, and testable code using Java (preferably Java 17)
• Ensure code quality through testing, reviews, and best practices
• Participate in CI/CD pipelines, deployments, and release management
• Support application operation (L2/L3), including troubleshooting, bug fixing, and performance optimization
• Create and maintain technical documentation (architecture, APIs, flows)
• Ensure security and compliance with internal standards
• Proactively identify risks, perform root cause analysis, and drive improvements
• Act as a senior team member, contributing to architecture decisions and mentoring junior developers
• Share knowledge within the team and contribute to continuous improvement of development practices

YOU WILL SUCCEED IF YOU:

• Education in Information Technology (Bachelor’s degree or higher)
• At least 5 years of experience in software development
• Strong experience in Java backend development (advanced level)
• Solid understanding of software architecture and system design
• Good overview of IT systems, infrastructure, and application landscape
• Experience with modern development methodologies (Agile preferred)
• Hands-on experience with:
  • version control systems (e.g., Git)
  • build tools and development environments
  • bug tracking and collaboration tools
• Experience with microservices architecture, APIs, and distributed systems
• Familiarity with databases, application servers, and middleware
• Basic knowledge of UML or similar modeling approaches
• Strong analytical thinking and problem-solving skills
• Good communication skills and ability to work in a team
• English – Upper intermediate (B2)

WHY SHOULD YOU CHOOSE US?

We believe in balance between work and personal life. An attractive and extensive work-life balance portfolio guarantees lasting motivation for employees and thus a better quality of life, promotes physical and mental well-being and contributes to a positive work environment. All this with the aim of providing more freedom in reconciling work, career growth, private life and individual lifestyle. Therefore we offer to our employees over 25 different benefits to improve their personal and professional life in these areas:

• Financial benefits
• Benefits with focus on learning and development
• Benefits with focus on health and sport
• Benefits with focus on family and work – life balance
• Other benefits

For more information about our benefits click to Benefits

Salary

Final salary is negotiable.

We are offering base salary depending on seniority level and previous experience of candidate. In addition to base salary we provide variable part and other financial benefits. Base salary will not be lower than 3100 € /brutto.

Additional information

* Please be informed that our remote working possibility is only available within Slovakia due to European taxation regulation.