Backend/Full-Stack Developer

Holisticon Connect is a division within NEXER GROUP, a custom software development company started in Poland in 2017 with a team of over 140 people. The company works with world-renowned brands from Scandinavia, the UK, and Western Europe. The role involves joining an international product team building a large-scale internal system used daily across multiple markets, playing a key role in digital transformation with scalable, event-driven microservices in a cloud environment.

• At least 5 years of experience working as a Backend Developer
• Excellent knowledge of Kotlin and Spring Boot
• Solid understanding of SQL, preferably PostgreSQL
• Very good command of English (C1), both written and spoken
• Hands-on experience designing services in a microservices architecture
• Experience working with Apache Kafka and asynchronous communication
• Ability to work in a cloud environment including AWS and Kubernetes
• Practical experience with Git and building REST APIs
• Practical knowledge of JavaScript or TypeScript and modern frontend development practices
• Practical understanding of frontend-backend integration and React application communication with backend services
• Understanding of system design fundamentals in distributed systems
• Experience writing unit, integration, and end-to-end tests in the Kotlin ecosystem
• Strong focus on clean, maintainable, and readable code
• Proactive, communicative team player with an open and collaborative mindset
• Based in Poland with availability for occasional in-person team meetings

Nice to have:

• Experience with Kubernetes and container orchestration
• Hands-on experience with cloud platforms, especially AWS
• Familiarity with event-driven and message-based architectures
• Experience working on large-scale or enterprise-level systems
• Experience with TypeScript and the modern React ecosystem
• Familiarity with frontend architecture, state management, and component-based design
• Understanding of usability and performance considerations in web applications
• Willingness to take ownership and influence technical decisions

• Design, develop, and maintain backend services using Kotlin and Spring Boot
• Build and evolve microservices with asynchronous communication patterns
• Implement and integrate event-driven solutions using Apache Kafka
• Work with relational databases, primarily PostgreSQL, ensuring data consistency and performance
• Develop and consume REST APIs used by frontend applications and other services
• Contribute to frontend application development using React, especially in areas closely connected to backend integrations and business logic
• Collaborate with Frontend Developers and UX Designers to deliver consistent, end-to-end solutions across backend services and user-facing applications
• Write unit, integration, and end-to-end tests within the Kotlin ecosystem
• Support frontend reliability and maintainability by designing clean service contracts and integration-friendly APIs
• Deploy and operate services in a cloud-native environment (AWS, Kubernetes)
• Participate in code reviews and contribute to engineering standards and best practices
• Use AI tools responsibly to improve development efficiency and code quality

Based in Poland, with availability for occasional in-person team meetings.