Senior Backend Engineer (Java, Kotlin, Spring Boot, AWS)

🏢 Summary: Senior backend engineering role focused on designing and scaling assortment management systems in a large retail ecosystem using Kotlin, Spring Boot, Kafka, AWS, and Kubernetes. The position involves building distributed, event-driven services, leading backend architecture evolution, and collaborating with cross-functional teams to deliver scalable enterprise solutions. The role also includes mentoring engineers, driving engineering best practices, and improving system reliability and observability. 🗂️ Requirements: Degree in Computer Science or comparable technical field, 6+ years of backend development experience, Experience with Kotlin, Experience with Spring Boot, Expertise in REST APIs, Experience with microservices, Experience with distributed systems, Experience with event-driven architectures, Hands-on experience with Kafka, Experience with asynchronous processing, Experience with AWS, Experience with Kubernetes, Experience with Amazon EKS, Experience with PostgreSQL, Experience with CI/CD, Experience with containerization, Knowledge of observability tooling, Knowledge of OAuth2, Knowledge of IAM, English proficiency, Polish proficiency, Readiness to work in hybrid model in Katowice 📃 Skills: Kotlin, Spring, SpringBoot, REST, Microservices, Kafka, AWS, Kubernetes, EKS, PostgreSQL, CI/CD, Docker, OAuth2, IAM 🏢 Description: Responsibilities 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. 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 standardized processes and scalable digital products that drive efficient support for one of Europe’s largest DIY retailers. Leveraging proven best practices, we advance the internationalization of products and the digital mindset of our partners, delivering consistent and business-critical solutions to support the targets of our customer. "

🏢 Summary: Backend and Cloud Engineer role focused on designing and scaling IoT-driven, cloud-native platforms in AWS. The position involves building distributed backend services, event-driven architectures, and telemetry processing systems while owning infrastructure and CI/CD pipelines. The engineer contributes to architecture decisions and ensures secure, scalable, and production-ready solutions. 🗂️ Requirements: University degree in Computer Science or related field, 5+ years of backend engineering experience, Strong expertise in TypeScript and Node.js, Hands-on experience with NestJS and scalable REST APIs, Deep experience with AWS services including IoT Core, Lambda, Kinesis, SQS, Timestream, IAM, CloudWatch, Experience with infrastructure as code and Kubernetes, Experience with containerization and CI/CD pipelines, Strong knowledge of distributed systems and event-driven architectures, Experience with IoT communication patterns such as MQTT, Fluent English and Polish, Availability for hybrid work (1–2 office visits per week) 📃 Skills: TypeScript, Node.js, NestJS, Fastify, REST, OpenAPI, AWS, IoT, IoTCore, Lambda, Kinesis, SQS, Timestream, IAM, CloudWatch, MQTT, PostgreSQL, Aurora, Terraform, OpenTofu, Kubernetes, Helm, GitLab, CI/CD 🏢 Description: Responsibilities We are looking for a strong backend and cloud engineer with deep experience in IoT and distributed systems who wants to shape and scale modern cloud - native platforms . You will design and evolve IoT and cloud architectures at OBI Smart Technologies Poland , working across device communication , telemetry processing and automation workflows . You act as a technical driver within the team, contributing to architecture decisions and ensuring scalable, secure and production-ready solutions across AWS environments . Your key responsibilities include: Design and develop scalable backend services using TypeScript, Node.js, NestJS and Fastify within distributed systems. Lead the design and evolution of REST APIs using OpenAPI standards and robust validation and versioning strategies. Design and operate AWS - native IoT and event-driven architectures using IoT Core, MQTT, Lambda, Kinesis and related services. Build scalable data processing and automation workflows for telemetry and energy-related data using Timestream , SQS and streaming services . Design and optimize persistence layers using PostgreSQL or Aurora and ensure data consistency and performance. Own infrastructure and deployment design using Terraform or OpenTofu , Kubernetes , Helm and GitLab CI/CD pipelines . Drive engineering best practices , observability , reliability and security standards while supporting GDPR-related backend processes and mentoring team members. Benefits 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. 5+ years of professional experience in backend engineering with strong expertise in TypeScript and Node . js . Strong hands-on experience with NestJS and designing scalable REST APIs in production environments. Deep experience with AWS cloud services including IoT Core , Lambda , Kinesis , SQS , Timestream , IAM and CloudWatch . Strong experience with infrastructure as code , Kubernetes , containerization and CI/CD pipelines . Solid understanding of distributed systems, event-driven architectures and IoT communication patterns such as MQTT . Ability to translate complex business requirements into scalable technical solutions. Fluent communication skills in English and Polish and availability to work in a hybrid mode with 1–2 office visits per week. 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 standardized processes and scalable digital products that drive efficient support for one of Europe’s largest DIY retailers. Leveraging proven best practices, we advance the internationalization of products and the digital mindset of our partners, delivering consistent and business-critical solutions to support the targets of our customer. "

🏢 Summary: The offer is for a senior backend and cloud engineer to design and scale IoT-driven, cloud-native platforms on AWS. The role focuses on building distributed systems, event-driven architectures, and scalable REST APIs using TypeScript and Node.js. It includes ownership of infrastructure, data processing workflows, and cloud-native deployments in production environments. 🗂️ Requirements: Completed degree in Computer Science or related field, 5+ years of backend engineering experience, Strong expertise in TypeScript, Strong expertise in Node.js, Hands-on experience with NestJS, Experience designing scalable REST APIs in production, Deep experience with AWS services, Experience with infrastructure as code, Experience with Kubernetes and containerization, Experience with CI/CD pipelines, Strong understanding of distributed systems, Knowledge of event-driven architectures, Experience with MQTT and IoT communication, Fluent English, Fluent Polish, Availability for hybrid work (1–2 days onsite per week) 📃 Skills: TypeScript, Node.js, NestJS, Fastify, REST, OpenAPI, AWS, IoT, IoTCore, Lambda, Kinesis, SQS, Timestream, IAM, CloudWatch, MQTT, PostgreSQL, Aurora, Terraform, OpenTofu, Kubernetes, Helm, GitLab, CI/CD 🏢 Description: Responsibilities We are looking for a strong backend and cloud engineer with deep experience in IoT and distributed systems who wants to shape and scale modern cloud - native platforms . You will design and evolve IoT and cloud architectures at OBI Smart Technologies Poland , working across device communication , telemetry processing and automation workflows . You act as a technical driver within the team, contributing to architecture decisions and ensuring scalable, secure and production-ready solutions across AWS environments . Your key responsibilities include: Design and develop scalable backend services using TypeScript, Node.js, NestJS and Fastify within distributed systems. Lead the design and evolution of REST APIs using OpenAPI standards and robust validation and versioning strategies. Design and operate AWS - native IoT and event-driven architectures using IoT Core, MQTT, Lambda, Kinesis and related services. Build scalable data processing and automation workflows for telemetry and energy-related data using Timestream , SQS and streaming services . Design and optimize persistence layers using PostgreSQL or Aurora and ensure data consistency and performance. Own infrastructure and deployment design using Terraform or OpenTofu , Kubernetes , Helm and GitLab CI/CD pipelines . Drive engineering best practices , observability , reliability and security standards while supporting GDPR-related backend processes and mentoring team members. Qualifications Completed university degree in Computer Science or a comparable technical field. 5+ years of professional experience in backend engineering with strong expertise in TypeScript and Node . js . Strong hands-on experience with NestJS and designing scalable REST APIs in production environments. Deep experience with AWS cloud services including IoT Core , Lambda , Kinesis , SQS , Timestream , IAM and CloudWatch . Strong experience with infrastructure as code , Kubernetes , containerization and CI/CD pipelines . Solid understanding of distributed systems, event-driven architectures and IoT communication patterns such as MQTT . Ability to translate complex business requirements into scalable technical solutions. Fluent communication skills in English and Polish and availability to work in a hybrid mode with 1–2 office visits per week. 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 standardized processes and scalable digital products that drive efficient support for one of Europe’s largest DIY retailers. Leveraging proven best practices, we advance the internationalization of products and the digital mindset of our partners, delivering consistent and business-critical solutions to support the targets of our customer. "

🏢 Summary: Senior/Staff Backend Engineer role focused on building and evolving a large-scale, event-driven platform using Java, Kafka Streams, and AWS. The position involves hands-on work with high-volume data flows, real-time stream processing, distributed systems, and production reliability. You will take strong technical ownership in a small team, shaping architecture, standards, and production readiness. 🗂️ Requirements: 7+ years of backend engineering experience, Strong hands-on experience with Java, Strong hands-on experience with Spring Boot, Deep production experience with Kafka Streams (topologies, joins, aggregations, windowing, state stores), Experience with event-driven or distributed systems, Hands-on experience with AWS services, Experience with Kubernetes and containerized deployments, Experience with PostgreSQL, MongoDB, and Redis, Strong knowledge of monitoring, debugging, and performance optimization, Ability to work independently in evolving technical environments, Professional English communication skills 📃 Skills: Java, Spring, Kafka, KafkaStreams, AWS, EKS, S3, SQS, SNS, Kinesis, Lambda, Kubernetes, PostgreSQL, MongoDB, Redis, Terraform, Helm, Prometheus, Grafana, Micrometer, Kotlin 🏢 Description: Senior / Staff Backend Engineer (Java, Kafka Streams, AWS) Location: Kraków, hybrid Contract: B2B or UoP B2B budget: up to 210 PLN/h + VAT Work model: around 3 days per week from the office We are looking for a Senior or Staff Backend Engineer to join a small, high-impact engineering team building a large-scale, event-driven platform. This is a hands-on role for someone who enjoys working close to real production systems: high-volume data flows, asynchronous processing, external integrations, reliability, observability and technical ownership. You will join a team where the codebase and domain are evolving, so this is a good opportunity for an engineer who does not need every problem to be fully defined before getting started. You will be expected to investigate, create structure, improve standards and make pragmatic technical decisions. What you will do Build and evolve backend services using Java and Spring Boot Design and maintain real-time event-processing flows using Kafka Streams Work with stream-processing concepts such as topologies, transformations, joins, aggregations, stateful processing and data routing Integrate external systems and infrastructure into a scalable internal platform Improve reliability, observability and production readiness of services handling high-volume data Investigate production issues, performance bottlenecks and data-flow problems Work with AWS, Kubernetes, PostgreSQL, MongoDB, Redis, Terraform and Helm Contribute to code reviews, architecture decisions, documentation and engineering standards Collaborate with product, platform and engineering stakeholders across an international environment What we are looking for 7+ years of backend engineering experience Strong, current hands-on experience with Java and Spring Boot Deep practical experience with Kafka Streams in production This should go beyond Kafka producers/consumers and include work with stream-processing logic, joins, aggregations, windowing, state stores or topology design Background in event-driven, distributed or real-time systems Hands-on AWS experience, ideally with services such as EKS, S3, SQS, SNS, Kinesis or Lambda Experience with Kubernetes , containers and production deployment environments Good understanding of databases such as PostgreSQL, MongoDB and Redis Strong production mindset: monitoring, debugging, reliability, performance and incident investigation Ability to work independently in an evolving and not always fully documented technical environment Clear English communication skills and confidence explaining technical topics to both engineers and non-technical stakeholders Nice to have Kotlin experience Experience with high-throughput data processing or streaming platforms Terraform, Helm, Prometheus, Grafana, Micrometer or similar observability tooling Experience in a small product team, scale-up or ownership-heavy engineering environment Familiarity with AI-assisted development tools What you can expect A technically challenging role focused on real production systems rather than isolated feature delivery Strong ownership Small team setup with room to influence architecture, standards and ways of working International engineering environment Clear recruitment process focused on practical engineering discussions Recruitment process Introductory conversation with the Hiring Manager Technical interview focused on Kafka/use cases and Java/code quality Final discussion with senior technical leadership The full company and product context will be shared during the first recruiter call.

🏢 Summary: Senior Backend Engineer role focused on transforming a mission-critical e-commerce domain supporting subscriptions and purchasing journeys for millions of users. The position centers on migrating a monolithic system to scalable microservices, improving performance and reliability, and shaping the future architecture of a global platform. Engineers will work with event-driven systems and modern AI tools while owning solutions end-to-end. 🗂️ Requirements: 5+ years of professional backend engineering experience, Strong experience designing and operating microservices architectures, Experience modernising legacy systems and decomposing monoliths, Solid understanding of distributed systems and scalable backend design, Commercial experience with Go, Java, Kotlin or Scala, Hands-on experience with Kafka or similar event-streaming technologies, Hands-on experience with PostgreSQL, Hands-on experience with Docker and Kubernetes, Experience with CI/CD pipelines, Practical experience using AI coding assistants (Claude Code, Cursor, Copilot or similar), Ability to review and validate AI-generated code, Comfortable owning solutions from idea to production 📃 Skills: Go, Golang, Java, Kotlin, Scala, Kafka, PostgreSQL, Docker, Kubernetes, CI/CD, GraphQL, DDD, TDD, BDD, Microservices 🏢 Description: Join a global e-commerce technology organisation serving millions of customers across multiple international markets. As a Senior Backend Engineer, you will become part of a team responsible for one of the company's most critical customer-facing domains. The platform supports customer subscriptions, plans, and purchasing journeys used daily by millions of users. This is not a maintenance role. The team is actively transforming a mission-critical domain, modernising legacy systems, reducing technical debt, and building the next generation of scalable services that will support future growth. You will play a key role in migrating core functionality from a monolithic architecture to modern microservices while helping shape the future architecture of a global platform. What You'll Do Build & Scale Core Services Design, develop, and maintain scalable backend services within a distributed microservices architecture. Build reliable systems supporting millions of customer interactions. Improve performance, reliability, and scalability across critical customer-facing services. Drive Modernisation Lead the migration of key business domains from monolithic systems to modern microservices. Reduce technical debt and improve long-term maintainability. Design solutions that support future platform growth. Shape Architecture Participate in architecture discussions and technical decision-making. Design orchestration layers supporting complex customer journeys and business processes. Help define engineering standards and best practices. Work with Event-Driven Systems Build and operate services powered by event-driven architectures. Work extensively with Kafka and real-time lifecycle events. Design resilient and observable distributed systems. Raise Engineering Standards Conduct code reviews and support other engineers through technical guidance. Promote best practices across software development, testing, deployment, and observability. Contribute to a strong culture of ownership and continuous improvement. AI-Powered Engineering Use modern AI tools and coding agents throughout the software development lifecycle. Leverage AI for onboarding, architecture exploration, implementation, testing, debugging, and productivity improvements. Apply engineering judgement to validate, verify, and safely integrate AI-generated outputs. What We're Looking For Backend Engineering Expertise 5+ years of professional backend engineering experience. Strong experience designing and operating microservices architectures. Experience modernising legacy systems and decomposing monoliths. Solid understanding of distributed systems and scalable backend design. Technical Stack Commercial experience with Go (Golang), Java, Kotlin or Scala Engineers coming from a JVM background should be open to working in a Go-driven environment. Hands-on experience with: Kafka or similar event-streaming technologies PostgreSQL Docker Kubernetes CI/CD pipelines Product & Ownership Mindset Comfortable owning solutions from idea through production. Strong problem-solving skills and ability to make technical trade-offs. Experience collaborating with product, business, and engineering stakeholders. AI Fluency Practical experience using AI coding assistants such as Claude Code, Cursor, Copilot, or similar tools. Understanding of how context, prompts, constraints, and validation influence AI-generated outputs. Ability to critically review and verify AI-generated solutions. Nice to Have Experience with subscription-based products. Experience in e-commerce environments. GraphQL knowledge. Familiarity with DDD, TDD, and BDD practices. What We Offer Opportunity to build systems used by millions of customers globally. High-impact engineering work with significant architectural ownership. International collaboration across distributed engineering teams. End-to-end ownership from idea to production. Hybrid working model (3 days per week in the Warsaw office). B2B cooperation model. 30 days of paid annual leave. Modern office located in Warsaw city centre. Continuous learning and professional growth opportunities.

🏢 Summary: Backend-focused Software and Cloud Engineer role focused on building scalable IoT and cloud-native platforms in AWS. The position involves developing backend services, designing REST APIs, and implementing event-driven architectures for device communication and telemetry processing. You will also contribute to infrastructure, deployment, and data processing workflows in production cloud environments. 🗂️ Requirements: Completed degree in Computer Science or related technical field, 3+ years of backend development experience with TypeScript and Node.js, Strong knowledge of REST API design and NestJS, Hands-on experience with AWS services (Lambda, S3, SQS, IoT Core), Experience with PostgreSQL and ORM tools, Basic experience with containerization, CI/CD, and infrastructure as code, Understanding of cloud-native or event-driven architectures 📃 Skills: TypeScript, Node.js, NestJS, Fastify, OpenAPI, AWS, Lambda, S3, SQS, IoTCore, MQTT, Kinesis, Timestream, PostgreSQL, Aurora, TypeORM, Terraform, OpenTofu, Docker, CICD, Vue, REST 🏢 Description: Responsibilities We are looking for a hands-on software and cloud engineer with a strong backend focus who wants to grow within IoT and cloud-native systems . You will contribute to building scalable IoT and cloud platforms at OBI Smart Technologies Poland , working on systems handling device communication , telemetry ingestion , and automation workflows . You collaborate closely with backend engineers, architects and product teams to deliver reliable and production-ready solutions across AWS -based environments. Your key responsibilities include: Develop and maintain backend services using TypeScript, Node.js, NestJS and Fastify . Design and implement REST APIs using OpenAPI standards and validation patterns . Contribute to AWS - based IoT and event-processing architectures including IoT Core, MQTT and telemetry ingestion . Support development of data processing and automation workflows using Lambda, SQS, Kinesis and Timestream . Work with PostgreSQL or Aurora databases and maintain persistence layers using TypeORM . Contribute to infrastructure and deployment processes using Terraform or OpenTofu , Docker and CI/CD pipelines . Support monitoring , testing , observability and operational stability while occasionally contributing to frontend components in Vue 3. Benefits 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. 3+ years of experience in backend development using TypeScript and Node.js . Good knowledge of REST API design and frameworks such as NestJS. Hands-on experience with AWS services such as Lambda, S3, SQS or IoT Core . Experience working with relational databases such as PostgreSQL and ORM tools. Basic experience with containerization , CI/CD pipelines and infrastructure as code tools. Understanding of cloud-native or event-driven architectures Fluent communication skills in English and Polish and availability to work in a hybrid mode with 1–2 office visits per week. 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 standardized processes and scalable digital products that drive efficient support for one of Europe’s largest DIY retailers. Leveraging proven best practices, we advance the internationalization of products and the digital mindset of our partners, delivering consistent and business-critical solutions to support the targets of our customer. "

🏢 Summary: Staff Engineer role focused on leading the design, evolution, and reliability of a high-scale distributed backend platform that generates and distributes real-time customer offers. The position combines deep hands-on backend engineering with architectural leadership in event-driven systems. It emphasizes scalability, performance, observability, and operational excellence in a complex production environment. 🗂️ Requirements: Experience owning complex backend systems end-to-end in scalable production environments, Proven experience designing and operating distributed systems, Strong backend engineering expertise in Java, Solid understanding of JVM performance, Hands-on experience with Apache Kafka, Hands-on experience with Spring Boot and/or Vert.x, Hands-on experience with Redis, Hands-on experience with OpenSearch or Elasticsearch, Experience with observability tools such as Datadog, Grafana, or Kibana, Strong system design skills in event-driven and asynchronous architectures, Knowledge of concurrency and non-blocking system design, Experience with scalability, resiliency, and fault-tolerance strategies, Experience debugging production incidents in distributed environments 📃 Skills: Java, JVM, Kafka, Spring, Vert.x, Redis, OpenSearch, Elasticsearch, Datadog, Grafana, Kibana, Kubernetes 🏢 Description: ABOUT THE ROLE We are looking for a passionate and highly experienced Staff Backend Engineer to help lead the design, development, reliability, and evolution of a complex distributed backend platform. This role is ideal for someone who enjoys going deep into understanding both the technical and business context behind problems, not just implementing solutions mechanically. We value engineers who are curious, proactive, and driven by learning - people who enjoy experimenting, challenging assumptions, and troubleshooting complex systems until the root cause is fully understood. As a Staff Backend Engineer, you will provide technical leadership across architecture, engineering practices, and platform evolution while remaining hands-on when needed. You will help teams make better technical decisions, raise engineering standards, simplify complex systems, and create solutions that balance business needs with long-term platform health. We're looking for someone who is comfortable working in ambiguity, treats failure as an opportunity to learn, welcomes constructive feedback, and leads through collaboration, ownership, and execution rather than authority. ABOUT YOUR FUTURE PLATFORM TEAM We build and operate a critical backend platform that generates, validates, and distributes customer-facing offers across multiple markets in real time. The system sits at the intersection of pricing, configuration, compliance, and localization - where milliseconds matter, correctness is non-negotiable, and small mistakes can have large-scale impact. Our systems apply complex configuration and licensing rules, handle market and event-level blocking, manage multi-language localization, and transform raw pricing data into customer-ready offers consumed across the ecosystem. We process high-throughput event streams, deal with constantly changing data, and solve problems that require both strong engineering fundamentals and deep domain understanding. Success means no incorrect or missing offers in production, near real-time reflection of pricing and configuration changes, fully compliant offers across jurisdictions, and seamless multi-language experiences for customers. Our ecosystem is built around: Event streaming and backbone: Apache Kafka Backend services: Java 23+ with Spring Boot and Vert.x (we are continuously evolving toward highly reactive, asynchronous, and event-driven architecture) State and performance optimization: Redis Search and analytics: OpenSearch / Elasticsearch Observability and operations: Datadog, Grafana, Kibana Runtime and scalability: Kubernetes-based containerized infrastructure We are actively evolving our platform toward more reactive, asynchronous, and event-driven architectures, making this an exciting environment for engineers who enjoy distributed systems, performance, concurrency, and real-time data processing challenges. WHAT YOU'LL DO Technical Leadership Leading architecture and design discussions for scalable, resilient distributed systems Collaborating with Architects and senior engineers to define solution approaches and evaluate new technologies through spikes and PoCs Improving and simplifying existing system designs while maintaining high engineering standards for performance, correctness, and maintainability Maintaining a strong engineering bar across quality, scalability, and maintainability Platform Reliability & Engineering Excellence Proactively identifying scalability, reliability, and performance risks across the platform Leading debugging and root cause analysis for complex production incidents Improving observability, monitoring, alerting, and operational readiness Driving technical debt reduction and continuous platform improvement Promoting best practices across event-driven systems, resiliency patterns, performance optimization, testing, automation, and CI/CD Team Enablement & Collaboration Supporting day-to-day technical coordination within the team and contributing to incident handling and engineering discussions Mentoring engineers through design reviews, code reviews, and hands-on technical guidance Supporting cross-team collaboration and helping troubleshoot integration and platform issues Encouraging a culture of collaboration, clarity, and shared ownership Actively participating in engineering communication channels and helping unblock others Delivery & Execution Working closely with Product, Engineering Managers, and Architects to translate ideas into executable technical solutions Helping define and break down EPICs and technical initiatives in Jira Driving clarity in ambiguous or complex technical initiative Ensuring alignment between short-term delivery needs and long-term platform evolution WHAT WE'RE LOOKING FOR Required Experience: Experience owning complex backend systems end-to-end in scalable production environments Proven experience designing and operating distributed systems Strong backend engineering expertise in Java, with solid understanding of JVM performance Hands-on experience with: Apache Kafka and event-driven architectures Spring Boot and/or Vert.x Redis for low-latency and stateful use cases OpenSearch / Elasticsearch for querying and analytics Observability tools such as Datadog, Grafana, or Kibana Strong system design skills, including: Event-driven and asynchronous architectures Concurrency and non-blocking system design Scalability, resiliency, and fault-tolerance strategies Evaluating trade-offs between latency, throughput, and consistency Experience debugging production incidents in distributed environments Strong communication skills and ability to influence technical decisions across teams Proactive mindset with strong ownership and accountability Comfortable working in complex, fast-paced engineering environments Collaborative approach and willingness to support and mentor others Nice to Have: Kubernetes and cloud-native infrastructure experience Experience building internal platforms or shared engineering frameworks SRE mindset and operational excellence practices Experience with real-time or high-throughput data systems Experience leading cross-team technical initiatives WHAT SUCCESS LOOKS LIKE Teams rely on you for technical direction and practical problem-solving The platform becomes more reliable, scalable, and easier to operate over time Production incidents decrease due to proactive engineering and improved system design Cross-team dependencies are better coordinated and easier to manage Engineering quality and consistency improve across services and squads Engineers grow technically through your mentorship and guidance WHAT WE OFFER Competitive salary aligned with your experience, expertise, and impact A collaborative, inclusive, and fast-paced engineering environment where ideas are welcomed, ownership is encouraged, and continuous learning is valued Hybrid work policy 4 weeks of Workation (T&C apply) Benefits package - 800 PLN net (B2B)/gross (UOP) monthly with access to the cafeteria platform (private medical care, insurances, sports card) Training budget ICAS assistance program that can provide help and guidance during challenging moments. Our office provides complimentary snacks and drinks; on Mondays, we serve complimentary breakfast. Team and office social events throughout the year Free parking for bicycles and motorcycles Free gym in the building Equipment: MacBook Pro + smartphone (iPhone 16/17 or Samsung Galaxy S25)

🏢 Summary: Mid/Senior Backend Developer role focused on building and scaling cloud-native, data-driven backend systems for retail media and headless advertising platforms. The position involves designing high-performance, multi-tenant services for ad serving, campaign delivery, targeting, analytics, and reporting across distributed environments. You will work with modern DevOps and streaming technologies to ensure scalability, reliability, and real-time data processing. 🗂️ Requirements: Completed degree in Computer Science, Mathematics, Physics or related field, Proven experience as Mid or Senior Backend Developer in production environments, Strong expertise in NestJS, NodeJS, and TypeScript, Hands-on experience with AWS and cloud-native architectures, Solid knowledge of Kubernetes and distributed systems, Practical experience with Terraform, Helm, and GitLab CI/CD, Experience with Kafka or similar streaming platforms, Experience with monitoring and logging tools including Grafana, Loki, Thanos, Experience with multi-tenant and large-scale architectures, Background in online marketing, retail media, or ad tech platforms, Fluency in English and Polish 📃 Skills: NestJS, NodeJS, TypeScript, AWS, Kubernetes, Terraform, Helm, GitLab, Kafka, Grafana, Loki, Thanos, CI/CD, Docker 🏢 Description: Responsibilities As a Mid or Senior Backend Developer, you will join one of our engineering teams working on the technology platforms that enable OBI’s retail media and First Media capabilities across digital and physical channels. You will contribute to building scalable, data driven backend systems that allow brands to activate media, distribute content, and measure performance along the entire customer journey, from inspiration and planning through to purchase and engagement. You will work on backend services that power headless ad serving, campaign delivery, content distribution, targeting, analytics, and reporting across OBI’s owned channels. These platforms operate at scale, support multi-tenant publisher use cases, and require high reliability and performance for internal product teams and external advertising partners. You will work closely with product, DevOps, and data teams to design, build, and operate backend services that enable real time activation, data processing, and reporting, while ensuring availability, performance, and operational stability across the media technology stack. Key Responsibilities: Design, build, and maintain backend services using NestJS, NodeJS, and TypeScript. Architect and scale headless advertising platforms and backend services for online marketing and retail media use cases. Contribute to the architecture and scaling of distributed, cloud native systems running on AWS and Kubernetes . Collaborate closely with DevOps teams to manage infrastructure using Terraform, Helm, and GitLab CI/CD. Implement and operate event driven and streaming solutions using Kafka . Ensure high availability, performance, and reliability through strong observability practices. Use Grafana, Loki, and Thanos to monitor systems , analyze logs, and support incident response. Actively participate in code reviews, architectural discussions, and technical decision making. Contribute to continuous improvement initiatives across performance, scalability, security, and operational excellence. Support and evolve large scale publisher platforms, multi-tenant content management systems, and advertising platforms. Benefits 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 you 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 Successfully completed university degree in (business) computer science, (business) mathematics, physics or similar. Proven experience as a Mid-level or Senior Backend Developer in production environments. Deep expertise in NestJS, NodeJS, and TypeScript. Hands on experience with AWS and cloud native architectures. Solid knowledge of Kubernetes, containerized workloads, and distributed systems. Practical experience with Terraform, Helm, and GitLab CI/CD. Experience working with Kafka or comparable messaging and streaming platforms. Strong background in monitoring and alerting, including metrics, logging, and incident response. Hands on experience with Grafana, specifically Loki and Thanos. Experience working in large scale organizations with complex stakeholder and system landscapes. Proven background in online marketing platforms, retail media, headless ad servers, or ad tech ecosystems. Experience operating or integrating large scale publisher platforms and content management systems. Strong understanding of multi-tenant architectures and information architectures at scale. Strong collaboration skills and the ability to work across engineering, product, and operations. Fluency in English and Polish. Openness to hybrid work in our Katowice office and collaboration across international teams. 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 standardized processes and scalable digital products that drive efficient support for one of Europe’s largest DIY retailers. Leveraging proven best practices, we advance the internationalization of products and the digital mindset of our partners, delivering consistent and business-critical solutions to support the targets of our customer. "

🏢 Summary: Hands-on Tech Lead role focused on designing and delivering scalable backend platforms and RESTful microservices for a global e-commerce and wellness technology ecosystem. The position involves technical leadership, backend development with Kotlin/Java and Spring Boot, mentoring engineers, and driving architecture decisions in a cloud-native environment. The role offers a hybrid work model in Warsaw with a competitive salary and benefits. 🗂️ Requirements: 6+ years of software development experience, Backend development experience with Java or Kotlin, Experience building and scaling RESTful microservices, Hands-on experience with Spring Boot, Hands-on experience with Docker, Hands-on experience with Kubernetes, Experience with AWS or GCP, Experience with PostgreSQL, MongoDB, DynamoDB, or Elasticsearch, Experience with unit testing and test-driven development, Experience with CI/CD pipelines, Experience leading technical projects and mentoring engineers, Ability to guide architecture decisions and delivery planning, Experience working in agile cross-functional teams 📃 Skills: Kotlin, Java, Spring, SpringBoot, Microservices, Docker, Kubernetes, AWS, GCP, PostgreSQL, MongoDB, DynamoDB, Elasticsearch, CI/CD, Datadog, REST, TDD, DevOps, Agile 🏢 Description: We are hiring on behalf of our client, a global innovator in fitness and wellness technology. Their mission is to empower people to live fit, strong, long, and happy lives by delivering integrated experiences to millions of members anytime, anywhere. We are looking for a Kotlin/Java Tech Lead to join an e-commerce engineering team. In this role, you will lead the design and delivery of scalable backend platforms and services powering the company's customer-facing commerce experience across web, retail, and other sales channels. This is a hands-on technical leadership role. You will guide engineering decisions, mentor other engineers, partner closely with product and design, and help the team deliver high-impact initiatives with strong engineering quality, scalability, and reliability. Key takeaways: Stack: Kotlin/Java, Spring Boot, microservices, Docker, Kubernetes, AWS, PostgreSQL, CI/CD, Datadog, technical leadership experience Salary: 26 000 PLN - 30 000 PLN gross on the Contract of Employment Working model : Hybrid - 3 days/week from the office Location: ul. Grzybowska, Warsaw Recruitment process : A call with MOTIFE Recruiter Panel interviews with the team (coding, architecture, and cross-collaboration interviews) Responsibilities: Technical Leadership Lead the delivery of small to large engineering initiatives, from technical discovery through implementation and production readiness. Guide the team in making strategic backend architecture decisions that support scalability, performance, and long-term maintainability. Own technical trade-offs and ensure solutions are aligned with business goals, user needs, and engineering standards. Mentor engineers through design reviews, code reviews, and day-to-day technical collaboration. Backend Engineering Build and improve backend platforms and services. Design and scale RESTful microservices used across web, retail, and other sales channels. Develop backend services using technologies such as Java, Kotlin, Spring Boot, Docker, and Kubernetes. Work with data stores such as PostgreSQL, MongoDB, DynamoDB, Elasticsearch, or similar technologies. Delivery & Product Collaboration Partner closely with product managers, designers, and peer engineers to scope, build, and deliver end-to-end features. Translate product strategy and business requirements into reliable, scalable technical solutions. Drive iterative delivery in an agile engineering environment. Maintain strong relationships with stakeholders and ensure clear communication around scope, risks, and delivery progress. Engineering Excellence Promote strong engineering practices, including unit testing, test-driven development, CI/CD, observability, and production ownership. Apply a DevOps mindset to build services that are reliable, observable, and easy to operate. Requirements: Technical Expertise 6+ years of professional software development experience. Strong backend engineering experience with Java or Kotlin. Proven experience building and scaling RESTful microservices. Hands-on experience with Spring Boot, Docker, and Kubernetes. Experience with cloud infrastructure such as AWS or GCP. Familiarity with data stores such as PostgreSQL, MongoDB, DynamoDB, Elasticsearch, or similar technologies. Experience with unit testing, test-driven development, and CI/CD pipelines. Leadership Experience Experience leading engineers to deliver high-impact technical projects. Proven ability to mentor junior and mid-level engineers and support their technical growth. Ability to guide technical decision-making, architecture discussions, and delivery planning. Experience with end-to-end feature ownership in a cross-functional product environment. Collaboration & Mindset Strong communication skills and ability to work effectively with product, design, and engineering stakeholders. Agile mindset with a strong focus on iterative design and delivery. High ownership, strong delivery orientation, and ability to operate in a fast-moving engineering environment. Strong desire to learn, share knowledge, and help engineers achieve their highest potential. What we offer: 100% paid medical care Multisport Creative tax (KUP) Home office allowance MacBook Pro Apply now If you enjoy technical leadership, hands-on backend engineering, and building platforms used at scale, this role is a strong opportunity to make a real impact. Please apply via our careers page and submit your CV in English.

🏢 Summary: The role involves designing and developing scalable backend systems in a microservices architecture using Java or Kotlin and Spring. The engineer will influence technical decisions while building payment and subscription platforms with event-driven communication and cloud-based solutions. The position includes working with modern architectural patterns and ensuring high code quality through testing and reviews. 🗂️ Requirements: Strong experience with Java and/or Kotlin, Solid knowledge of Spring and Spring Boot, Hands-on experience with SQL and relational databases, Experience with PostgreSQL, Proven experience with microservices architecture, Experience with event-driven systems, Practical experience with JUnit, Mockito, Testcontainers, Experience with AWS or GCP, Understanding of DDD, CQRS, Hexagonal Architecture, Experience with payment or subscription systems 📃 Skills: Java, Kotlin, Spring, SpringBoot, SQL, PostgreSQL, Microservices, Kafka, JUnit, Mockito, Testcontainers, AWS, GCP, DDD, CQRS, HexagonalArchitecture 🏢 Description: Senior Backend Engineer (Java/Kotlin) We are looking for an experienced Backend Engineer to join a team building modern, scalable systems based on a microservices architecture. This role offers real influence over technical decisions, system architecture, and the quality of delivered solutions—particularly within payment and subscription platforms. Responsibilities Design, develop, and maintain backend systems using Java or Kotlin and the Spring Framework Build and evolve microservices following DDD , CQRS , and Hexagonal Architecture principles Implement event-driven communication , ideally using Apache Kafka Work with relational databases ( PostgreSQL or other SQL databases ) and optimize queries Write unit and integration tests using JUnit, Mockito, and Testcontainers Contribute to the design and development of cloud-based solutions ( AWS or GCP ) Participate in code reviews and drive high engineering standards Collaborate closely with product and engineering teams to deliver business-critical features Requirements Strong experience with Java and/or Kotlin Solid knowledge of Spring / Spring Boot Hands-on experience with SQL and relational databases (preferably PostgreSQL ) Proven background in microservices-based architectures Experience with event-driven systems (Kafka is a strong plus) Practical experience with backend testing (JUnit, Mockito, Testcontainers) Experience working with cloud platforms ( AWS or GCP ) Good understanding of Domain-Driven Design (DDD) , CQRS , and Hexagonal Architecture Must-have: experience with payment systems and/or subscription-based platforms Nice to Have Experience working with high-scale, high-availability systems Knowledge of security and transactional data handling Background in product-driven, Agile environments