Ruby Developer

🏢 Summary: Senior Backend Engineer role focused on defining the technical direction and architecture of a domain within a borderless financial platform. The position involves designing scalable microservices, driving architectural decisions, and leading a small backend team in a distributed environment. The role emphasizes reliability, security, and high‑volume transaction processing in a cloud-based ecosystem. 🗂️ Requirements: 4-7 years backend engineering experience, Proficiency in Go, Experience with Java 21 or modern Java, Experience designing microservices with clear contracts, Experience with caching strategies including TTL and invalidation, Experience with event-driven or asynchronous architectures, Experience with structured logging, metrics, and alerting, Experience with AWS services, Experience with relational and non-relational databases, Experience with Spring Boot or similar frameworks, Experience reviewing code and architectural decisions, Availability to work in GMT+5:30 timezone 📃 Skills: Java, Go, Spring, JDBI, PostgreSQL, CockroachDB, DynamoDB, Redis, SQS, SNS, Kafka, AWS, EKS, ALB, RDS, S3, Kong, Datadog, Quickwit, JWT, RBAC, TLS, Docker, ArgoCD, GitHub, Microservices, Kafka, CDC 🏢 Description: Project overview This project focuses on developing a borderless financial platform that supports international banking flows, payments, account management and regulatory compliant operations. The product handles sensitive data and high volume transactions while prioritising reliability and security. Team You will work in a distributed environment with backend engineers, a product manager and platform specialists. The role involves leading a sub team of three to five engineers, conducting design reviews, ensuring code quality standards and supporting collaborative decision making. Position overview We are looking for a Senior Backend Engineer who will define the technical direction of a backend domain and drive architectural decisions. You will design microservices, create scalable solutions, guide a small engineering group and collaborate closely with product specialists to shape the delivery roadmap. We are looking for a person willing to work in the time zone: GMT+5:30. Technology stack Java 21, Go, Spring Boot, JDBI, custom workflow engines, PostgreSQL, CockroachDB, DynamoDB, Redis, SQS, SNS, Kafka, AWS EKS ALB RDS S3 Secrets Manager, Kong API Gateway, Datadog, Quickwit, JWT RBAC TLS request and response encryption VAPT, GitHub Actions, Docker, ArgoCD, microservices, event driven architecture, saga and orchestration patterns, CDC pipelines, maker checker workflows Responsibilities Plan and design backend microservices with clear boundaries and contracts Develop solutions for domains such as onboarding, payments, transaction orchestration or platform components Break complex epics into actionable tasks with clear acceptance criteria Review designs from other engineers to ensure scalability and fault tolerance Drive technical decisions including caching layers, asynchronous processing strategies, database choices and API versioning Evaluate build versus buy options for integrations and services Collaborate with a product manager to align on scope and prioritisation Lead a sub team of backend engineers and support their professional growth Support incident response, root cause analysis and long term improvements Monitor service performance using logging, metrics and tracing tools Requirements Professional backend engineering experience from 4-7 years Experience with Go (tooling & CLIs) Experience designing microservices with well-defined contracts and boundaries Experience with Java 21 or modern Java versions Experience with caching strategy design, including TTL and invalidation approaches Experience working with asynchronous processing, event-driven architecture, or queue-based workflows Experience using structured logging, metrics, and alerting to debug production systems Experience in making build versus buy decisions with clear trade-off analysis Experience reviewing code and identifying architectural or contract issues Experience with AWS-based services Experience working with relational and non-relational databases such as PostgreSQL or DynamoDB Experience writing backend services using Spring Boot or similar frameworks Nice to have Experience with financial or payments related systems Experience with KYC or AML flows Experience with workflow or orchestration engines Experience with platform wide pattern creation or reusable service design Experience with data encryption practices and security audits Experience with CockroachDB or high availability distributed databases What We Offer: Vacation days : Up to 26 business days per year. 10 illness/special days off per year (fully paid, no medical papers needed) for all contract types Health and life insurance (Luxmed) MyBenefit platform with Multisport option Internal psychological support service English language classes from the first working day Access to external learning platforms : O’Reilly, LinkedIn Learning, Udemy, and a wide catalog of diverse internal training Flexible workplace : work from the office, from home, or choose a hybrid option Tech Skills Mentoring Program Opportunities to develop as a public speaker, mentor, or technical interviewer Fully paid idle (bench) when not involved in a project Certification reimbursement (AWS, GCP, Microsoft, etc.)

🏢 Summary: Senior/Lead Ruby on Rails role focused on leading backend architecture and development while supporting frontend integration with React. The position involves driving technical direction, ensuring scalability and performance, and maintaining high code quality across the project. The role also acts as a technical point of contact aligning engineering outcomes with business goals. 🗂️ Requirements: Mastery of Ruby on Rails, Expert-level Ruby proficiency, Experience designing scalable backend architectures, Experience with React, Proven experience leading technical projects or modules, Ability to conduct code reviews and enforce best practices 📃 Skills: Ruby, Rails, React, Backend, Architecture, REST, Git, SQL 🏢 Description: We are looking for a high-level Ruby on Rails Expert to take a key role in the development team. This position is designed for someone who excels in backend architecture but can also navigate the frontend landscape when needed. As a Senior or Lead Developer, you will be responsible for the technical direction of the project, ensuring high performance, and maintaining a robust codebase while communicating effectively with international stakeholders. Responsibilities Technical Leadership: Leading the backend development lifecycle using Ruby on Rails . Architecture: Designing and implementing scalable, secure, and maintainable backend services. Full-stack Support: Collaborating on the frontend layer, specifically with React (experience here is a big plus). Code Quality: Conducting code reviews, mentoring team members, and establishing best development practices. Communication: Acting as a technical point of contact, ensuring clear alignment between technical goals and business needs. Requirements Expertise: Mastery of Ruby on Rails and the Ruby language. Frontend: Practical experience with React (highly desirable). Ownership: Proven ability to lead projects or significant technical modules. Soft Skills: Proactive attitude, strong problem-solving skills, and a "Lead" mindset.

🏢 Summary: The offer is for a Ruby on Rails Developer to build and maintain modern web applications for a new project, contributing to scalable solutions and microservices architecture. The role involves working with Ruby on Rails as the core technology, with exposure to Node.js and React, in a collaborative and agile environment. 🗂️ Requirements: Proven commercial experience with Ruby on Rails, Experience building modern web applications, Experience with Node.js and/or React, Understanding of microservices architecture, Ability to participate in code reviews and follow coding standards, Very good English skills 📃 Skills: Ruby, Rails, Node.js, React, Microservices, REST, Git 🏢 Description: We are seeking a skilled Ruby on Rails Developer to join our team for an exciting new project. Responsibilities Develop and maintain web applications using Ruby on Rails as the primary technology. Collaborate with cross-functional teams to design and implement scalable solutions. Contribute to the architecture and development of microservices, where applicable. Utilize Node.js and React technologies to enhance application features and performance. Participate in code reviews and ensure adherence to best practices and coding standards. Communicate effectively with stakeholders to understand project requirements and deliver solutions accordingly. Qualifications Proven commercial experience in Ruby on Rails development. Experience working with modern web applications and frameworks. Exposure to Node.js and/or React technologies. Understanding of microservices architecture is preferred. Strong problem-solving skills and ability to work collaboratively within a team setting. Very good English level. Benefits Opportunity to participate in a cutting-edge project with a dynamic and innovative team. Professional growth through engagement in technical interviews and project development phases. Remote work (Poland). Exposure to a diverse technology stack including Ruby on Rails, Node.js, React, and microservices. Unique TEAL culture, relationship- and respect-driven community, non-corporate atmosphere. Agile approach and no bureaucracy. Outstanding integration trips to various places in Europe for all employees. Activities to support your well-being and health. Luxmed Gold Extended medical care and Multisport Plus benefit.

🏢 Summary: Senior role focused on developing and maintaining a business applications ecosystem (CRM, document workflows, ERP and AI integrations) using Ruby on Rails. The position involves building integrations, processing documents, handling background jobs and realtime features, and deploying to self-managed Linux VPS infrastructure. It requires working on production systems and solving complex backend and integration challenges. 🗂️ Requirements: Very good knowledge of Ruby on Rails, Strong understanding of backend application architecture, Strong knowledge of SQL and relational databases, Experience with integrations and API design/debugging, Experience with background jobs and asynchronous processing, Ability to work with Linux/VPS environments 📃 Skills: Ruby, Rails, ActiveRecord, ActiveJob, SolidQueue, ActionCable, ActionMailer, ActionMailbox, MySQL, MSSQL, TinyTds, SQL, REST, KSeF, Claude, IMAP, Backblaze, Linux, Ubuntu, Puma, systemctl, crontab, logrotate, Tailscale, CombinePDF, Node.js, ERP, VPS 🏢 Description: Senior Ruby on Rails Backend Engineer Szukamy doświadczonego Ruby on Rails Backend Developera do rozwijania naszego ekosystemu aplikacji biznesowych (CRM, obieg dokumentów, workflow, integracje ERP, KSeF, automatyzacje procesów). Projekt obejmuje: integracje z systemami zewnętrznymi, przetwarzanie dokumentów, background jobs, kolejki, realtime events, deployment na własnej infrastrukturze VPS, integracje AI i ERP. To rola dla osoby, która dobrze odnajduje się w systemach produkcyjnych i lubi rozwiązywać realne problemy biznesowe. Idealnie, jeśli jesteś z okolic Trzebini / Chrzanowa — preferujemy osoby, z którymi możliwa będzie okazjonalna współpraca stacjonarna przy planowaniu i wdrożeniach. Stack technologiczny Backend / Rails Ruby on Rails 7.2 Active Record Active Job + Solid Queue Action Mailer Action Cable Action Mailbox Bazy danych MySQL MS SQL Server (TinyTds) migracje Rails indeksy JSON columns Integracje KSeF REST API Claude API (Anthropic) IMAP polling Backblaze B2 TinyTds / Optima ERP Deployment / infrastruktura Linux VPS (Ubuntu) Puma systemctl crontab logrotate Tailscale VPN Dokumenty / PDF CombinePDF generowanie i stemplowanie PDF Node.js CLI wrappers Szukamy osoby, która: ma bardzo dobrą znajomość Ruby on Rails, rozumie architekturę aplikacji backendowych, dobrze zna SQL i relacyjne bazy danych, potrafi projektować i debugować integracje, ma doświadczenie z background jobs i async processing, swobodnie pracuje na Linux/VPS. Mile widziane doświadczenie z KSeF, doświadczenie z ERP, znajomość MSSQL, doświadczenie z realtime systems, integracje AI, doświadczenie z dużymi workflow dokumentowymi. Oferujemy realny wpływ na architekturę systemów, dużą samodzielność, brak korporacyjnych procesów, ciekawe integracje i problemy techniczne, możliwość długoterminowej współpracy. Forma współpracy B2B lub FV full-time lub part-time zdalnie / hybrydowo

🏢 Summary: B2B contract opportunity for an experienced Ruby on Rails Backend Developer to design, build, and maintain scalable backend services and production-grade APIs in a remote-first environment. The role focuses on delivering high-quality, reliable, and performant solutions in close collaboration with cross-functional teams. Candidates will work in an agile setup, contributing to architecture decisions, automated testing, and continuous improvement initiatives. 🗂️ Requirements: 4+ years of commercial experience with Ruby on Rails, Experience building and maintaining production-grade APIs and backend systems, Knowledge of PostgreSQL and relational database design, Experience with RSpec and automated testing, Experience with AWS and/or Heroku, Understanding of software architecture principles and backend scalability, Experience working in Agile environments, English proficiency at B2+ level 📃 Skills: Ruby, Rails, PostgreSQL, RSpec, AWS, Heroku, Sidekiq, SQL, REST, Git 🏢 Description: About us LLInformatics is a forward-thinking IT consulting firm, trusted by clients across Europe and North America. We specialize in delivering complex projects on time, with exceptional quality, and always meeting the highest compliance standards. Our remote-first team of 130+ experts is passionate about building cutting-edge digital products that drive real results. With a focus on data-driven decisions, measurable outcomes, and a strategic mindset, we’re raising the bar in our industry—backed by a strong, collaborative work culture that fuels our success. Contract Type: B2B Location: Remote or in our Warsaw office Your Tasks and Responsibilities: Design, develop, and maintain backend features and APIs using Ruby on Rails. Build scalable backend services supporting business applications. Collaborate with Product, QA, and DevOps teams to deliver business-focused solutions. Improve application performance, reliability, maintainability, and scalability. Write clean, production-ready code with appropriate test coverage (unit and integration tests). Participate in code reviews and follow engineering best practices. Troubleshoot application issues and support production deployments. Participate in agile development processes and contribute to continuous improvement initiatives. Requirements: 4+ years of commercial Ruby on Rails experience. Strong experience building and maintaining production-grade APIs and backend systems. Good knowledge of PostgreSQL and relational database design. Experience with RSpec and automated testing. Experience with AWS and/or Heroku. Understanding of software architecture principles and backend scalability concepts. Experience working in Agile environments. Strong communication skills in English (B2+). Nice to Have: Experience with background processing solutions (e.g., Sidekiq). Experience with monitoring, observability, and performance optimization. Experience working with international teams and stakeholders. Why join us? Flexible Working Hours – We focus on results! Manage your time, keep your team informed about your availability, and attend key meetings. Work from Anywhere – Choose your ideal setup! Work 100% remotely within the EU , go hybrid , or enjoy our Warsaw office , fully equipped for productivity. Comprehensive Onboarding – From day one, we ensure you feel comfortable and supported, so you can quickly become part of the team. Flat Structure – We value initiative and open communication. Every voice matters here! Positive Company Culture & Team Spirit – We create an environment where everyone feels appreciated and comfortable. Modern Work Methods – We use cutting-edge project management techniques inspired by the IT world. Transparent Communication – Regular 360° feedback sessions and mentor support to help you grow. Top-Notch Equipment – Get a MacBook for your work. If you choose to work from our Warsaw office , you'll also have access to a 34” (16:9) widescreen monitor and an ergonomic standing desk . Weekly English Lessons – Optional classes with a native speaker to help you improve your skills.

🏢 Summary: Full-Stack Developer (Ruby on Rails) role within an R&D team building advanced life science research platforms. The position involves designing and delivering scalable, secure web solutions across frontend and backend, contributing to architecture and product direction. The engineer will work in an agile environment to enhance a multi-tenant SaaS platform used globally by researchers. 🗂️ Requirements: Minimum 3 years of professional web development experience, Strong hands-on experience with Ruby on Rails, Solid backend and frontend development knowledge, Experience with HTML, CSS, and JavaScript, Experience building and maintaining APIs, Experience with AWS and CI/CD pipelines, Proficiency with Git, Experience with AI-assisted development tools, Ability to develop scalable and secure applications 📃 Skills: Ruby, Rails, HTML, CSS, JavaScript, Hotwire, React, AWS, CI/CD, Git, Docker, MySQL, Elasticsearch, APIs 🏢 Description: For one of our clients, we are currently seeking an experienced Full‑Stack Developer (Ruby on Rails) to join an R&D team building advanced platforms for life science research. This role is ideal for an engineer who values clean architecture, high‑quality code, and modern web development practices. You will become part of an agile, highly motivated engineering team responsible for building and evolving a platform used daily by researchers and laboratories worldwide. As an experienced engineer, you will play a meaningful role in shaping the technical direction of the product and driving future platform improvements. Working closely with product leaders and management, you will ensure that our solutions continue to meet the needs of a growing scientific community. What You Will Do Design, implement, and ship new features as well as future releases of the platform across frontend and backend layers. Build, improve, and maintain robust platform APIs with a strong focus on scalability, reliability, and performance. Write clear, maintainable, and well‑tested code, following iterative and test‑driven development principles. Collaborate closely with product and management teams to transform business requirements into effective technical solutions. Help develop a highly scalable service deployed in multi‑tenant SaaS, single‑tenant SaaS, and on‑premise environments. Apply secure development practices and contribute to system scalability and performance optimization. Actively use AI‑assisted development tools to speed up coding, reviews, and testing workflows. Contribute positively to team collaboration, sharing ownership and fostering a supportive and enjoyable work culture. Experience & Technical Requirements Required: Minimum of 3 years of professional experience in web development, with solid knowledge of both backend and frontend development. Required: Strong, hands‑on experience with Ruby on Rails . Experience with several of the following technologies: HTML, CSS, JavaScript, Hotwire, React, AWS, CI/CD pipelines, Git . Experience with Docker is considered an advantage. Experience with MySQL is a plus. Experience with Elasticsearch is a plus. Hands‑on use of AI‑powered tools to accelerate development (e.g. AI‑assisted coding, automated code reviews, or testing). Experience integrating AI workflows into the software development lifecycle is considered a nice‑to‑have. Who You Are A collaborative team member who raises the technical bar and encourages excellence in others. Comfortable explaining ideas, designs, and decisions to both technical and non‑technical stakeholders. Able to thrive in a fast‑paced, agile environment where results are delivered in short cycles. Opinionated about technology choices and how to apply them effectively to deliver real value to users and the business. A pragmatic yet passionate polyglot programmer with a strong software engineering foundation. Open to experimenting with and adopting AI tools as part of everyday development work. Willing to work from the office at least two days per week, with flexibility to work remotely when needed. A background or degree in Life Sciences is a significant advantage. Hays Poland sp. z o.o. jest agencją zatrudnienia zarejestrowaną w rejestrze prowadzonym przez Marszałka Województwa Mazowieckiego pod numerem 361.

🏢 Summary: Full-Stack / Backend Developer role focused on building and maintaining scalable applications and REST APIs that support client products. The position involves developing new integrations, enhancing existing backend and frontend systems, and improving platform performance and reliability. You will contribute to architecture improvements and work within a cloud-based environment. 🗂️ Requirements: Minimum 3 years commercial experience, Experience with Java, Experience with Spring Boot, Experience with AWS, Experience with MongoDB, Experience with PostgreSQL, Experience with React.js, Experience designing REST APIs, Knowledge of backend architecture, Experience with cloud environments, Understanding of clean code principles, Experience working in Agile environment 📃 Skills: Java, SpringBoot, AWS, MongoDB, PostgreSQL, React, REST, Agile, Cloud, Architecture 🏢 Description: We are looking for an experienced Full-Stack / Backend Developer to join our team and help build scalable applications and APIs supporting our clients’ products. You will work on both backend and frontend solutions, contributing to product development, system improvements, and ongoing platform stability. Your Responsibilities Develop new APIs to support client integrations and business features. Maintain and enhance existing backend and frontend applications. Fix bugs and improve application performance and reliability. Upgrade and support operational aspects of the platform. Identify opportunities to improve product quality, architecture, and development processes. Collaborate with developers, product teams, and stakeholders to deliver high-quality solutions. Participate in code reviews and contribute to best engineering practices. Required Skills Minimum 3 years of commercial experience with: Java Spring Boot AWS MongoDB PostgreSQL React.js Experience designing and developing REST APIs. Knowledge of backend architecture and modern web applications. Experience working with cloud-based environments (AWS). Understanding of software development best practices and clean code principles. Ability to work in an Agile development environment.

🏢 Summary: Senior Ruby on Rails Developer role focused on building and evolving a cloud-ready product into a scalable, distributed system. The position involves designing architecture, developing core services and APIs, and driving Kubernetes-based deployments with CI/CD automation. You will influence engineering standards and contribute production-ready code in a greenfield development environment. 🗂️ Requirements: 5+ years of software engineering experience, Senior-level Ruby on Rails expertise, Experience building and scaling distributed systems, Knowledge of Kubernetes, Experience with CI/CD pipelines, Experience with Infrastructure as Code, Strong API design skills, Experience with microservices communication, Ability to lead architectural initiatives, Mentoring experience for engineers 📃 Skills: Ruby, Rails, Kubernetes, CI/CD, IaC, API, Microservices, DistributedSystems 🏢 Description: We are looking for an experienced Senior Ruby on Rails Developer to join the team responsible for development of the product, which is evolving into a modern, cloud‑ready solution. In this role, you will have opportunity to influence architectural decisions, contribute production‑ready code, and collaborate closely with cross‑functional teams. Your daily responsibilities: Build and improve core platform services and APIs Design scalable, distributed system architecture Implement and optimize key components in the codebase Set engineering standards for reliability and maintainability Drive deployments using Kubernetes and CI/CD automation Collaborate across teams to align technical and product goals. Requirements: 5+ years of software engineering experience, including senior‑level work Strong proficiency in Ruby on Rails Experience building and scaling distributed systems Solid knowledge of Kubernetes, CI/CD, and IaC Strong skills in API design and microservice communication Ability to lead architectural initiatives and mentor other engineers. What we offer: Attractive salary and benefits package, including Multisport card, insurance, and medical care Hybrid work from the Krakow office International work environment in a product company Training and development opportunities within the organization Joining the greefield project with pure development. Apply now!

🏢 Summary: Senior Ruby on Rails engineer role focused on designing and building scalable, production-grade backend systems and APIs in a remote-first environment. The position involves architectural decision-making, performance optimization, mentoring, and close collaboration with cross-functional teams. The offer includes flexible remote work within the EU, modern equipment, and a strong engineering culture emphasizing quality and automation. 🗂️ Requirements: 6+ years commercial experience with Ruby on Rails, Strong experience building production-grade APIs and backend systems, Advanced knowledge of PostgreSQL, Experience with database optimization and data modeling, Strong experience with RSpec and automated testing, Experience with AWS and/or Heroku, Understanding of distributed systems and system architecture, Experience working in Agile environments, English proficiency at B2+ level 📃 Skills: Ruby, Rails, PostgreSQL, RSpec, AWS, Heroku, APIs, SQL, Git, Agile 🏢 Description: About us LLInformatics is a forward-thinking IT consulting firm, trusted by clients across Europe and North America. We specialize in delivering complex projects on time, with exceptional quality, and always meeting the highest compliance standards. Our remote-first team of 130+ experts is passionate about building cutting-edge digital products that drive real results. With a focus on data-driven decisions, measurable outcomes, and a strategic mindset, we’re raising the bar in our industry—backed by a strong, collaborative work culture that fuels our success. Contract Type: B2B Location: Remote or in our Warsaw office Your Tasks and Responsibilities: Design, develop, and own complex backend features and APIs using Ruby on Rails. Architect scalable, reliable, and maintainable backend services. Collaborate closely with Product, QA, DevOps, and business stakeholders to translate requirements into technical solutions. Drive improvements in system performance, scalability, reliability, and engineering quality. Write clean, production-grade code with strong automated test coverage. Review code, establish engineering standards, and contribute to architectural decisions. Troubleshoot complex production issues and support stable, efficient deployments. Participate in agile delivery processes and drive continuous improvement initiatives. Mentor other engineers and actively contribute to knowledge sharing within the team. Requirements: 6+ years of commercial Ruby on Rails experience. Strong experience designing and building production-grade APIs and backend systems. Advanced knowledge of PostgreSQL, database optimization, and data modeling. Strong experience with RSpec, automated testing, and engineering best practices. Experience with AWS and/or Heroku. Good understanding of distributed systems, scalability, and system architecture. Experience working in Agile environments. Strong communication skills in English (B2+). Nice to Have: Technical leadership or mentoring experience. Experience with observability, monitoring, and performance optimization. Experience participating in architectural discussions and technical decision-making. Experience working directly with international stakeholders. Why join us? Flexible Working Hours – We focus on results! Manage your time, keep your team informed about your availability, and attend key meetings. Work from Anywhere – Choose your ideal setup! Work 100% remotely within the EU , go hybrid , or enjoy our Warsaw office , fully equipped for productivity. Comprehensive Onboarding – From day one, we ensure you feel comfortable and supported, so you can quickly become part of the team. Flat Structure – We value initiative and open communication. Every voice matters here! Positive Company Culture & Team Spirit – We create an environment where everyone feels appreciated and comfortable. Modern Work Methods – We use cutting-edge project management techniques inspired by the IT world. Transparent Communication – Regular 360° feedback sessions and mentor support to help you grow. Top-Notch Equipment – Get a MacBook for your work. If you choose to work from our Warsaw office , you'll also have access to a 34” (16:9) widescreen monitor and an ergonomic standing desk . Weekly English Lessons – Optional classes with a native speaker to help you improve your skills.

🏢 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.