Senior Backend Engineer with Java

🏢 Summary: Oferta dotyczy roli Senior Backend Engineer odpowiedzialnej za rozwój wysokowydajnej platformy inwestycyjnej i tradingowej obsługującej miliony użytkowników. Stanowisko obejmuje projektowanie architektury mikroserwisowej, rozwój backendu w Java i Go oraz optymalizację systemów działających pod dużym obciążeniem. Kandydat będzie współpracować z zespołami Product, DevOps i Engineering oraz uczestniczyć w decyzjach architektonicznych i mentoringu. 🗂️ Requirements: 8-12 lat doświadczenia w programowaniu backendowym, Bardzo dobra znajomość Java, Bardzo dobra znajomość Golang, Doświadczenie z JVM, Doświadczenie w projektowaniu systemów high scale i high throughput, Bardzo dobra znajomość architektury mikroserwisowej, Doświadczenie z REST API, Doświadczenie z integracjami systemowymi, Znajomość MongoDB, Znajomość PostgreSQL, Znajomość MySQL, Znajomość indeksowania, cachingu i optymalizacji wydajności, Znajomość Linux, Znajomość podstaw sieci i komunikacji między komponentami, Umiejętność analizy logów i troubleshootingu, Doświadczenie w branży finansowej lub fintech, Znajomość języka angielskiego na poziomie B2 📃 Skills: Java, Golang, JVM, REST, MongoDB, PostgreSQL, MySQL, Linux, Microservices, API, Caching, Networking, AWS, GCP, Azure, Oracle, CI/CD, DevOps 🏢 Description: Dołącz do jednej z najszybciej rozwijających się firm technologicznych z sektora finansowego, która tworzy nowoczesną platformę inwestycyjną i tradingową wykorzystywaną przez użytkowników na całym świecie. To organizacja stawiająca na wysoką jakość inżynierii, skalowalność oraz nowoczesną architekturę. Produkty obsługują miliony użytkowników, bardzo duży ruch i wymagają rozwiązań zapewniających wysoką dostępność oraz wydajność. Twoja rola Jako Senior Backend Engineer będziesz odpowiadać za projektowanie i rozwój kluczowych komponentów platformy oraz współtworzenie architektury systemów działających pod dużym obciążeniem. Do Twoich obowiązków będzie należeć: projektowanie, rozwój i utrzymanie backendu w Java i Go, tworzenie oraz rozwój architektury mikroserwisowej, projektowanie i rozwój wydajnych API oraz integracji z systemami wewnętrznymi i zewnętrznymi, optymalizacja wydajności aplikacji oraz rozwiązywanie problemów produkcyjnych, analiza logów, diagnostyka i troubleshooting złożonych problemów, współpraca z zespołami Product, DevOps oraz Engineering przy dostarczaniu nowych funkcjonalności, udział w code review oraz dbanie o wysoką jakość kodu, mentoring mniej doświadczonych programistów, udział w podejmowaniu decyzji architektonicznych i rozwoju platformy. Szukamy osoby, która posiada 8-12 lat doświadczenia w programowaniu backendowym, bardzo dobrą znajomość Java i Golang, praktyczne doświadczenie z JVM, doświadczenie w projektowaniu i rozwijaniu systemów o wysokiej dostępności oraz dużym ruchu (high scale, high throughput), bardzo dobrą znajomość architektury mikroserwisowej, doświadczenie z REST API oraz integracjami systemowymi, praktyczną znajomość baz danych (MongoDB, PostgreSQL, MySQL), w tym indeksowania, cachingu i optymalizacji wydajności, dobrą znajomość systemu Linux oraz podstaw działania sieci i komunikacji między komponentami aplikacji, umiejętność diagnozowania problemów, analizy logów oraz proponowania usprawnień technicznych, doświadczenie w branży finansowej lub fintech, znajomość języka angielskiego na poziomie min. B2. Mile widziane doświadczenie z rozwiązaniami DevOps oraz CI/CD, znajomość chmur publicznych (AWS, GCP lub Azure), doświadczenie z Oracle Cloud, znajomość wzorców architektonicznych, doświadczenie w obszarze tradingu, giełdy, kryptowalut lub High-Frequency Trading (HFT), wykształcenie techniczne, znajomość języka arabskiego.

🏢 Summary: Senior Backend Engineer role focused on building and scaling backend systems for an AI-driven product that transforms complex government data into actionable insights. The position involves designing data ingestion, processing pipelines, and distributed infrastructure from scratch, with full ownership from architecture to production. You will work closely with a small senior team to deliver scalable, production-ready systems. 🗂️ Requirements: 6+ years of Backend Engineering experience, Experience in JVM ecosystem, Experience in product companies (B2B SaaS preferred), Experience designing and owning backend systems in production, Strong knowledge of system design and scalability, Experience building asynchronous or distributed systems, Ability to make and justify technical decisions, Fluency in English, Valid work authorization in Europe or LATAM 📃 Skills: Kotlin, Java, JVM, SQL, GCP, Messaging, Queues, DistributedSystems, SystemDesign, DataPipelines, LLMs, AI 🏢 Description: About the role We’re looking for a Senior Backend Engineer to join our early team and help build our product from zero to one. You’ll work on a product that helps companies navigate complex government data, from contracts and grants to market signals and turn it into actionable insights using AI. On the backend side, this means working on data ingestion, processing, and the infrastructure that powers search and AI-driven workflows at scale. You’ll collaborate closely with a small, senior team and have real ownership, from shaping solutions to shipping them to production and improving them over time. You might be a fit if you: Must have: 6+ years of experience as a Backend Engineer, preferably in the JVM ecosystem (we use Kotlin on the backend) Experience working in product companies (B2B SaaS preferred) with direct impact on shipped features Experience working in small companies or startups would be a strong advantage Experience designing and owning backend systems in production (from initial design to deployment and ongoing improvements) Strong understanding of system design, including scalability, failure handling, and trade-offs Experience building asynchronous or distributed systems (e.g. messaging, queues, event-driven systems) Ability to make and justify technical decisions, not just implement given solutions Fluency in written and spoken English Nice to have: Experience with large-scale data processing, scraping, or data pipelines Experience working with LLMs / AI-related systems Experience with GCP or similar cloud environments How We Work Build Bridges to Help Customers Win - We pride ourselves on being obsessively customer-centric. Shooting Star Speed - We move with extreme speed. We value momentum, decisiveness, and the ability to accelerate when it matters. Fun Is a Feature - Fun is a Feature means we intentionally design Starbridge to be an energizing place to do hard work. Joy, humor, and camaraderie make great teams faster, sharper, and more resilient. In the Arena - We believe the best ideas come from living close to the work, feeling the friction, hearing the nuance, and experiencing the details firsthand. Benefits include: Competitive salary + early-stage equity Unlimited PTO Regular off-sites (NYC + global locations) Interview Process We move fast — really fast. Getting back to someone today beats tomorrow, and our interview process reflects that mindset. Please keep us posted on your timeline so we can move quickly and speed things up where needed. After submitting your application, the team reviews your CV and statement of exceptional work. If your application passes this stage, you will be invited to a 30-minute interview during which a member of our team will make sure you're a good fit for the role. You will have the opportunity ask questions and learn more about the role as well. We'll then send you a programming challenge that consists of two parts: LeetCode and SQL. Beyond that step, you will enter the main process, which consists of three interviews: System design exercise hands-on. Live coding in Java/Kotlin. Product thinking and past work. All interviews will be conducted via Google Meet. Eligibility to Work in Europe or LATAM: Candidates must hold valid authorization to work in the country where they will be based. At this time, we are unable to offer visa sponsorship or assist with work permit applications.

🏢 Summary: Senior Backend Engineer role focused on building and scaling backend microservices for consumer-facing platforms and internal data privacy systems. The position involves developing distributed, event-driven systems supporting personalization, search, and regulatory compliance at scale. It requires strong experience in JVM technologies and cloud-native environments. 🗂️ Requirements: Strong commercial experience with JVM-based languages (Java or Scala), Experience with Kotlin or willingness to learn, Solid understanding of microservices architecture, Experience with event-driven systems, Experience with Docker and Kubernetes, Hands-on CI/CD experience in production, Experience with unit and integration testing, Experience with relational databases and SQL, Ability to design and maintain scalable distributed systems 📃 Skills: Java, Scala, Kotlin, JVM, Microservices, Docker, Kubernetes, CI/CD, SQL, PostgreSQL, AWS, Terraform, Elasticsearch, MongoDB, GraphQL, Go, Python 🏢 Description: We are looking for a Senior Backend Engineer to join a fast-growing product organization working on consumer-facing platforms and internal data systems. This role is suited for an experienced backend engineer who is comfortable building scalable, reliable services across different domains, from customer-facing journeys to data privacy and compliance infrastructure. About the Project: You will contribute to backend systems that power core customer experiences and internal platform initiatives. Depending on the team, this includes scaling a menu and personalization platform for high-traffic consumer applications, or building a centralized Data Privacy Service handling regulatory compliance (GDPR, CCPA) and Data Subject Requests at scale. Both streams require strong engineering fundamentals, a microservices mindset, and the ability to deliver in complex, distributed environments. Responsibilities: Design, develop, and maintain scalable backend microservices across consumer or data platform domains; Build systems supporting search, personalization, customer targeting, and engagement; Develop and operate services ensuring regulatory compliance and secure data handling (GDPR, CCPA); Work with event-driven architectures and distributed systems; Contribute to CI/CD pipelines, testing practices, and overall engineering quality; Collaborate with product and engineering teams to deliver reliable and performant solutions. Qualifications: Strong commercial experience with JVM-based languages (Java, Scala, or similar); Experience with Kotlin, or willingness to learn it on the project; Solid understanding of microservices architecture and event-driven systems; Experience with Docker and Kubernetes; Hands-on CI/CD experience in a production environment; Experience with unit and integration testing; Familiarity with relational databases (e.g. PostgreSQL) and SQL; AWS and Terraform experience is a plus; Experience with Elasticsearch, MongoDB, or GraphQL is a plus; Go or Python knowledge is a nice to have; Background in e-commerce, subscription platforms, or data privacy systems is a plus. Recruitment Process: Initial interview with our recruitment team; Interview with the hiring manager; Live Coding Assessment; Meeting with the Project Manager. Inuits Sp. z o.o. is registered in the National Register of Employment Agencies (KRAZ) under number 35420.

🏢 Summary: Senior Backend Engineer role focused on designing and scaling a high-throughput, event-driven platform. The position centers on building and optimizing large-scale event processing services and APIs in distributed systems. It involves solving complex scalability and reliability challenges in a massive-scale environment. 🗂️ Requirements: Senior-level experience in backend development, Strong Python expertise, Experience scaling message queue systems, Experience with distributed systems and microservices architecture, Proven track record building high-throughput backend services, Experience designing scalable and fault-tolerant systems, Ability to implement and optimize APIs 📃 Skills: Python, Azure, ServiceBus, StorageQueues, EventHubs, Microservices, DistributedSystems, APIs, EventDriven, EventSourcing, Streaming, Observability, Monitoring 🏢 Description: Location: Remote Type: Full-time Level: Senior Duration: 4 months Start: ASAP We are looking for an experienced Senior Backend Engineer to join a team responsible for building and scaling a high-throughput, event-driven platform operating at massive scale. Your primary focus will be the event processing backbone — designing, developing, and optimizing services that handle large volumes of messages reliably and efficiently. You will work closely with architects and other senior engineers to implement APIs that expose data and support advanced triage and processing workflows. This role is ideal for someone who enjoys solving hard scalability problems , working with distributed systems, and building resilient backend services that operate under real-world load. Responsibilities Design and build backend services responsible for large-scale event processing Optimize and scale message-based systems to handle high throughput and reliability requirements Implement APIs defined by system architects to expose data and collect processing results Collaborate with cross-functional teams to improve platform performance and resilience Contribute to architectural decisions around scalability, fault tolerance, and observability Core Skills Strong experience with Python as a primary backend language Deep expertise in scaling message queue systems (e.g. Azure Service Bus, Storage Queues, Event Hubs or similar) Solid understanding of microservices architecture and distributed systems Proven experience building high-throughput, resilient backend services Strong problem-solving skills and ability to work with complex systems Highly Desirable Experience with event-driven or event sourcing architectures Background in data processing frameworks or streaming systems Experience building platforms related to observability, monitoring, or large-scale event management Familiarity with designing systems for fault tolerance and graceful degradation What we offer Work on technically challenging systems operating at very large scale High level of autonomy and real influence on system architecture Collaboration with experienced engineers in a mature engineering environment Competitive compensation and flexible working model Project with strong technical ownership

🏢 Summary: Senior Java Spring Boot Backend Developer role focused on building and modernizing a cloud-native Messaging Delivery Platform in the financial sector. The position involves designing and developing scalable microservices, APIs, and distributed systems deployed on Kubernetes and AWS. You will contribute to high-quality backend solutions within an Agile environment using modern DevOps and cloud practices. 🗂️ Requirements: Minimum 6 years of commercial experience in Java development, Strong hands-on experience with Spring Boot, Practical experience in microservices architecture, Experience with Kubernetes and AWS cloud environments, Proficiency with CI/CD tools: Jenkins, GitHub, Maven, Groovy, Strong knowledge of API design: Swagger, OpenAPI, REST, JSON, Experience with OAuth2 and API Gateway solutions such as Kong, Experience with unit testing and TDD practices, Knowledge of Agile methodologies, especially Scrum, Fluent English, Legal right to work in the EU 📃 Skills: Java, Spring, SpringBoot, Microservices, Kubernetes, AWS, Jenkins, GitHub, Maven, Groovy, Swagger, OpenAPI, REST, JSON, OAuth2, Kong, Docker, CICD, TDD, Scrum 🏢 Description: Unleash innovation at scale — drive the future of cloud-native, microservices architectures! Krakow-based opportunity with hybrid work model (3 remote days per week). As a Senior Java Spring Boot Backend Developer , you will be working for our client in the financial industry, focusing on the Messaging Delivery Platform—centralizing and modernizing message delivery to bank customers across multiple channels. Join a cutting-edge project that shapes the future of client communication through advanced distributed systems and cloud technology. Your main responsibilities: Develop high-quality, scalable backend applications using Java and Spring Boot, ensuring adherence to technical requirements and standards. Collaborate within a multidisciplinary Agile team to design, build, and enhance distributed microservices architectures. Implement and monitor API solutions using Swagger, OpenAPI, REST, and JSON standards, ensuring best practices. Deploy and manage containerized applications on Kubernetes, leveraging AWS cloud infrastructure. Integrate authentication and authorization mechanisms such as OAuth 2 and API Gateway solutions. Write and execute unit tests, contribute to automation testing efforts, and uphold quality benchmarks. Participate in code reviews, challenge implementations to maintain highest quality standards, and promote innovation. Keep abreast of current technologies, tools, and industry best practices, continuously enhancing your expertise. Support and mentor team members to foster a culture of technical excellence and knowledge sharing. You're ideal for this role if you have: Minimum 6 years of experience in Java development within a senior or expert capacity. Strong hands-on expertise with Spring Boot framework and microservices architecture. Practical experience with Kubernetes and Cloud environments, particularly AWS. Proficiency with CI/CD tools such as Jenkins, GitHub, Maven, and Groovy scripting. Deep understanding of API design principles, including Swagger, OpenAPI 3.0, REST, and JSON. Familiarity with authentication protocols like OAuth 2 and API Gateway solutions such as Kong. Robust knowledge of Agile practices, especially TDD and Scrum methodologies. Ability to work fluently in English, with excellent communication skills. It is a strong plus if you have: Certifications or additional experience with AWS services. Knowledge of automation testing frameworks. Experience with messaging systems or middleware. Eligibility for the role: Only candidates with an existing legal right to work in the European Union will be considered for this role. #MAKEYourCareerBETTER Interested? Apply now and include your CV (preferably in English) along with a statement confirming your consent to the processing and storage of your personal data.

🏢 Summary: Senior Java Spring Boot Backend Developer role focused on building and modernizing a cloud-native Messaging Delivery Platform in the financial sector. The position involves designing and developing scalable microservices, APIs, and distributed systems deployed on Kubernetes and AWS. You will work in an Agile team to deliver secure, high-quality backend solutions for multi-channel customer communication. 🗂️ Requirements: Minimum 6 years of Java development experience, Strong hands-on experience with Spring Boot, Experience designing microservices architectures, Practical experience with Kubernetes, Experience with AWS cloud environments, Proficiency with CI/CD tools (Jenkins, GitHub, Maven, Groovy), Strong knowledge of API design (Swagger, OpenAPI, REST, JSON), Experience with OAuth2 and API Gateway solutions (Kong), Experience with TDD and Scrum methodologies, Legal right to work in the European Union 📃 Skills: Java, Spring, SpringBoot, Microservices, Kubernetes, AWS, Jenkins, GitHub, Maven, Groovy, Swagger, OpenAPI, REST, JSON, OAuth2, Kong, CICD, TDD, Scrum, API 🏢 Description: Unleash innovation at scale — drive the future of cloud-native, microservices architectures! Krakow-based opportunity with hybrid work model (3 remote days per week). As a Senior Java Spring Boot Backend Developer , you will be working for our client in the financial industry, focusing on the Messaging Delivery Platform—centralizing and modernizing message delivery to bank customers across multiple channels. Join a cutting-edge project that shapes the future of client communication through advanced distributed systems and cloud technology. Your main responsibilities: Develop high-quality, scalable backend applications using Java and Spring Boot, ensuring adherence to technical requirements and standards. Collaborate within a multidisciplinary Agile team to design, build, and enhance distributed microservices architectures. Implement and monitor API solutions using Swagger, OpenAPI, REST, and JSON standards, ensuring best practices. Deploy and manage containerized applications on Kubernetes, leveraging AWS cloud infrastructure. Integrate authentication and authorization mechanisms such as OAuth 2 and API Gateway solutions. Write and execute unit tests, contribute to automation testing efforts, and uphold quality benchmarks. Participate in code reviews, challenge implementations to maintain highest quality standards, and promote innovation. Keep abreast of current technologies, tools, and industry best practices, continuously enhancing your expertise. Support and mentor team members to foster a culture of technical excellence and knowledge sharing. You're ideal for this role if you have: Minimum 6 years of experience in Java development within a senior or expert capacity. Strong hands-on expertise with Spring Boot framework and microservices architecture. Practical experience with Kubernetes and Cloud environments, particularly AWS. Proficiency with CI/CD tools such as Jenkins, GitHub, Maven, and Groovy scripting. Deep understanding of API design principles, including Swagger, OpenAPI 3.0, REST, and JSON. Familiarity with authentication protocols like OAuth 2 and API Gateway solutions such as Kong. Robust knowledge of Agile practices, especially TDD and Scrum methodologies. Ability to work fluently in English, with excellent communication skills. It is a strong plus if you have: Certifications or additional experience with AWS services. Knowledge of automation testing frameworks. Experience with messaging systems or middleware. Eligibility for the role: Only candidates with an existing legal right to work in the European Union will be considered for this role. #MAKEYourCareerBETTER Interested? Apply now and include your CV (preferably in English) along with a statement confirming your consent to the processing and storage of your personal data.

🏢 Summary: Senior Java Spring Boot Backend Developer role focused on building and modernizing a cloud-native Messaging Delivery Platform in the financial sector. The position involves developing scalable microservices, APIs, and containerized applications deployed on AWS using Kubernetes. It combines hands-on backend engineering with DevOps practices in an Agile environment. 🗂️ Requirements: Minimum 6 years of Java development experience, Strong hands-on experience with Spring Boot, Experience with microservices architecture, Practical experience with Kubernetes, Experience with AWS cloud environment, Experience with CI/CD tools (Jenkins, GitHub, Maven, Groovy), Strong knowledge of API design (REST, Swagger, OpenAPI, JSON), Experience with OAuth2 and API Gateway solutions, Experience working in Agile (Scrum, TDD), Legal right to work in the European Union 📃 Skills: Java, Spring, SpringBoot, Microservices, Kubernetes, AWS, Jenkins, GitHub, Maven, Groovy, REST, Swagger, OpenAPI, JSON, OAuth2, Kong, CI/CD, TDD, Scrum 🏢 Description: Unleash innovation at scale — drive the future of cloud-native, microservices architectures! Krakow-based opportunity with hybrid work model (3 remote days per week). As a Senior Java Spring Boot Backend Developer , you will be working for our client in the financial industry, focusing on the Messaging Delivery Platform—centralizing and modernizing message delivery to bank customers across multiple channels. Join a cutting-edge project that shapes the future of client communication through advanced distributed systems and cloud technology. Your main responsibilities: Develop high-quality, scalable backend applications using Java and Spring Boot, ensuring adherence to technical requirements and standards. Collaborate within a multidisciplinary Agile team to design, build, and enhance distributed microservices architectures. Implement and monitor API solutions using Swagger, OpenAPI, REST, and JSON standards, ensuring best practices. Deploy and manage containerized applications on Kubernetes, leveraging AWS cloud infrastructure. Integrate authentication and authorization mechanisms such as OAuth 2 and API Gateway solutions. Write and execute unit tests, contribute to automation testing efforts, and uphold quality benchmarks. Participate in code reviews, challenge implementations to maintain highest quality standards, and promote innovation. Keep abreast of current technologies, tools, and industry best practices, continuously enhancing your expertise. Support and mentor team members to foster a culture of technical excellence and knowledge sharing. You're ideal for this role if you have: Minimum 6 years of experience in Java development within a senior or expert capacity. Strong hands-on expertise with Spring Boot framework and microservices architecture. Practical experience with Kubernetes and Cloud environments, particularly AWS. Proficiency with CI/CD tools such as Jenkins, GitHub, Maven, and Groovy scripting. Deep understanding of API design principles, including Swagger, OpenAPI 3.0, REST, and JSON. Familiarity with authentication protocols like OAuth 2 and API Gateway solutions such as Kong. Robust knowledge of Agile practices, especially TDD and Scrum methodologies. Ability to work fluently in English, with excellent communication skills. It is a strong plus if you have: Certifications or additional experience with AWS services. Knowledge of automation testing frameworks. Experience with messaging systems or middleware. Eligibility for the role: Only candidates with an existing legal right to work in the European Union will be considered for this role. #MAKEYourCareerBETTER Interested? Apply now and include your CV (preferably in English) along with a statement confirming your consent to the processing and storage of your personal data.

🏢 Summary: Senior Backend Engineer role focused on designing and developing scalable, reliable backend services using Java. The position involves working in a cross-functional team to build high-performance systems, improve architecture, and support CI/CD and production environments. 🗂️ Requirements: 5+ years Backend Engineering experience, Strong Java proficiency, Solid knowledge of databases and SQL, Experience with RESTful APIs, Experience with microservices architecture, Experience with high-load systems, Experience with Docker and Kubernetes, Experience with AWS or GCP, Knowledge of CI/CD pipelines, Understanding of Agile practices 📃 Skills: Java, SQL, REST, Microservices, Docker, Kubernetes, AWS, GCP, CI/CD, Golang, Python 🏢 Description: We are looking for a Senior Backend Engineer with strong Java experience to help us design and develop scalable solutions. You will work in a cross-functional team, building reliable services and contributing to the continuous improvement of our systems. This role is ideal for someone who enjoys solving complex problems and driving technical excellence. 💼 Responsibilities: Design, develop, and maintain backend features and services. Collaborate with teams to define requirements and integrate systems. Ensure performance, scalability, and reliability of applications. Contribute to CI/CD processes and support production systems. Write clear documentation and share knowledge within the team. ✅ Requirements: 5+ years of experience as a Backend Engineer, with strong Java skills (Golang/Python is a plus). Solid understanding of databases and SQL. Experience with RESTful API design, microservices, and high-load systems. Familiarity with Docker, Kubernetes, and cloud environments (AWS/GCP). Knowledge of CI/CD pipelines and Agile practices. Strong problem-solving and communication skills. 🎁 We offer: Stable employment in a fast-growing company. Flexible and remote-friendly working model. Health and wellbeing benefits. Learning and development opportunities. Modern equipment and comfortable work environment.

🏢 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

🏢 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.