Senior Backend Engineer (Java, Kotlin)

Reply; Katowice; Hybrid; PLN 145,000 - 246,000; Full time

Benefits offered by this job

Salary range 13 000 - 22 000 PLN gross

Motivizer Benefits Platform

Language Courses

Ongoing training opportunities

Networking events

Job summary

OBI Smart Technologies, a Reply joint venture, seeks a senior backend engineer to design and scale core systems powering assortments across a large retail ecosystem. You will own backend architecture and evolve systems within the assortment management domain, building scalable services and integrations.

You will lead event-driven architectures with Kafka, work in AWS and Kubernetes environments, and collaborate with architects, product owners and stakeholders to deliver robust solutions.

Qualifications

• Degree in Computer Science or related field.
• 6+ years of backend development experience with Kotlin and Spring Boot.
• StrongREST APIs, microservices, distributed systems experience.
• Kafka and asynchronous processing in production.
• AWS and Kubernetes (Amazon EKS) in scalable environments.
• PostgreSQL data modeling and performance considerations.
• CI/CD, containerization, observability tooling, and security concepts (OAuth2, IAM).
• Proficient in English and Polish; hybrid work in Katowice.

Responsibilities

• Design and develop scalable backend services, APIs, and integrations using Kotlin and Spring Boot within distributed systems.
• Translate business and product requirements into robust, scalable system designs.
• Lead event-driven architectures and asynchronous processing with Kafka.
• Design and integrate backend systems in AWS and Kubernetes-based environments.
• Drive data modeling and persistence strategies with PostgreSQL and cloud-native approaches.
• Act as technical interface between business, product and engineering teams, leading solution design and backlog refinement.
• Promote engineering best practices, observability, reliability and architectural consistency; mentor peers.

Skills

Kotlin

Spring Boot

REST APIs

Microservices

Distributed systems

Kafka

AWS

Kubernetes

Amazon EKS

PostgreSQL

CI/CD

Containerization

Observability

Security concepts (OAuth2, IAM)

English and Polish communication

Education

Completed university degree in Computer Science

Tools

AWS

Kubernetes

Job description

We are looking for a strong backend engineer who wants to design and scale core systems powering product and assortment management across a large retail ecosystem.

You will take ownership of backend architecture and system evolution within the assortment management domain, building scalable services and integrations across a complex, event-driven enterprise landscape. You act as a technical driver within the team, working closely with architects, product owners and stakeholders to deliver robust, high-quality solutions.

Your key responsibilities include:

• Design and develop scalable backend services, APIs and integrations using Kotlin and Spring Boot within distributed systems.
• Translate complex business and product data requirements into robust, maintainable and scalable system designs.
• Lead the design and evolution of event-driven architectures and asynchronous processing using Kafka.
• Design and integrate backend systems within AWS and Kubernetes-based enterprise environments.
• Drive data modeling and persistence strategies using PostgreSQL and cloud-native approaches.
• Act as a technical interface between business, product and engineering teams, leading solution design and backlog refinement.
• Drive engineering best practices, observability, reliability and architectural consistency across the platform.
• Lead troubleshooting, optimization and continuous improvement initiatives while mentoring less experienced engineers.

Benefits

• Salary range for Employment Contract: 13 000 - 22 000 PLN gross/month.
• Motivizer Benefits Platform to choose and manage all your benefits in one place. You receive a budget (550 PLN monthly). You can choose medical care package, meal tickets, sports cards (we have Multisport and on preferential terms, we have membership cards to one of the most popular Gyms), cinema tickets, shop vouchers, discounts and many more.
• Language Courses - you'll have access to a multi-language learning platform enabling you to practice your language skills and learn new ones!
• Regular and systematic further training opportunities - both internally and from external providers. We support your ongoing learning and development.
• Cooperation within an internal community is our everyday reality. We have networking events, coding challenges, and company parties for different occasions.

Qualifications

• Completed university degree in Computer Science or a comparable technical field.
• 6+ years of professional experience in backend development using Kotlin and Spring Boot in complex environments.
• Strong expertise in REST APIs, microservices, distributed systems and event-driven architectures.
• Deep hands-on experience with Kafka and asynchronous processing patterns in production systems.
• Strong experience with AWS and Kubernetes (including Amazon EKS) in scalable environments.
• Solid experience with PostgreSQL and designing performant, reliable data models.
• Experience with CI/CD, containerization, observability tooling and modern security concepts (OAuth2, IAM).
• Strong communication skills in English and Polish, with readiness to work in a hybrid model in Katowice.

About OBI Smart Technologies

WHO ARE WE:

We are a joint venture between OBI and Reply Group, responsible for co-designing, building and operating mission-critical digital platforms for commerce, customer service, and omnichannel retail.

OUR MISSION:

"We unite technology leadership with deep retail vision to implement standardised processes and scalable digital products that drive efficient support for one of Europe’s largest DIY retailers. Leveraging proven best practices, we advance the internationalisation of products and the digital mindset of our partners, delivering consistent and business-critical solutions to support the targets of our customer."