Ruby on Rails Developer

🏢 Summary: B2B contract for a Ruby on Rails Developer to build and maintain a client platform, implement new features, and ensure performance and reliability in a remote or hybrid setup. The role involves backend development with Rails, testing, database management, and occasional frontend support with React. You will collaborate in an Agile team to deliver high-quality, production-ready solutions. 🗂️ Requirements: 3+ years experience with Ruby on Rails, Knowledge of Active Record, Knowledge of RSpec, Experience with production applications, Familiarity with relational databases, Experience writing unit and integration tests, Understanding of MVC architecture, Basic experience with React, Understanding of REST API principles, English B2 level minimum, Polish B2 level minimum, Familiarity with Agile methodologies 📃 Skills: Ruby, Rails, ActiveRecord, RSpec, PostgreSQL, React, REST, AWS, Heroku, Scrum, Kanban, MVC 🏢 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: Implementing new features on our client’s platform. Solving programming challenges and continuously developing your skills. Participating in code reviews and collaborating with team members. Maintaining the existing codebase and fixing bugs. Writing unit and integration tests (E2E is a plus). Supporting frontend development using React when needed. Contributing to product improvements through experimentation and iteration. Taking care of application performance and reliability. Collaborating with Product Managers and team members to deliver high-quality solutions. Requirements: 3+ years of experience with Ruby on Rails. Good knowledge of Active Record and RSpec. Experience working with production applications (AWS or Heroku is a plus). Familiarity with relational databases (e.g., PostgreSQL). Experience writing tests and understanding of testing best practices. Understanding of the MVC pattern or similar architectures. Basic experience with React (components, API integration). Understanding of REST API principles. English and Polish at a minimum B2 level. Familiarity with Agile methodologies (Scrum, Kanban). Nice to have: Experience with distributed systems. Interest in using AI tools to improve development workflow. 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: 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: 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: 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: Development role in an international team building a modern SaaS platform for the life science sector, focused on data management, process automation, and research tools. The position involves designing and developing a web application and APIs using Ruby on Rails, contributing to architecture decisions, and optimizing system performance and scalability. Work is carried out in an Agile environment with real impact on a global product. 🗂️ Requirements: Minimum 3 years of experience with Ruby on Rails, Experience building web applications, Experience with JavaScript, HTML, CSS, Experience designing and integrating APIs, Experience with AWS, Experience with CI/CD pipelines, Experience with Git version control, English proficiency at B2 level or higher, Availability for onsite onboarding (first 2 weeks) 📃 Skills: Ruby, Rails, JavaScript, HTML, CSS, API, AWS, CI/CD, Git, MySQL, Docker, ElasticSearch, Hotwire, React 🏢 Description: Dołącz do międzynarodowego zespołu pracującego nad nowoczesną platformą SaaS wykorzystywaną w obszarze life science. Projekt dotyczy rozwiązań wspierających zarządzanie danymi, automatyzację procesów oraz rozwój narzędzi badawczych wykorzystywanych przez organizacje na całym świecie. Lokalizacja biura: Wrocław. Model pracy: zdalnie w większości czasu pracy (praca z biura 1 raz na 2 tygodnie). Stack technologiczny projektu: Ruby on Rails, JavaScript, Hotwire / React, API, MySQL, AWS, Git, CI/CD, Docker, ElasticSearch . Zespół: liczy obecnie ok. 5 osób i działa w środowisku międzynarodowym. Zespół zlokalizowany jest częściowo w Polsce (Wrocław), Norwegii i Izraelu. Zakres obowiązków: Projektowanie i rozwój aplikacji webowej w Ruby on Rails Tworzenie i rozwój API platformy Implementacja nowych funkcjonalności oraz rozwój istniejących modułów Dbanie o jakość kodu (testy, utrzymanie, refaktoryzacja) Współpraca z zespołem produktowym oraz interesariuszami biznesowymi Udział w projektowaniu architektury i podejmowaniu decyzji technologicznych Optymalizacja wydajności oraz skalowalności systemu Wykorzystanie narzędzi AI wspierających proces developmentu (np. code review, generowanie kodu, testy) Praca w środowisku Agile w międzynarodowym zespole Główne wymagania: Minimum 3 lata doświadczenia w tworzeniu aplikacji webowych w Ruby on Rails Doświadczenie w pracy z JavaScript, HTML, CSS Znajomość pracy z API (projektowanie, integracje) Doświadczenie z AWS oraz CI/CD Doświadczenie z systemami kontroli wersji (Git) Znajomość języka angielskiego na poziomie min. B2 Umiejętność pracy w zespole oraz komunikacji w środowisku międzynarodowym Samodzielność, odpowiedzialność za realizowane zadania Gotowość do pracy stacjonarnej podczas onboardingu (2 pierwsze tygodnie pracy) Mile widziane: Doświadczenie z Hotwire lub React Doświadczenie z Docker, MySQL, ElasticSearch Doświadczenie w projektach SaaS Doświadczenie z narzędziami AI wspierającymi development Znajomość domeny life science Wyższe wykształcenie w obszaru nauk przyrodniczych Firma oferuje: Stałą, długofalową współpracę w oparciu o kontrakt B2B (+25 dni płatnego urlopu) Pracę zdalną w większości czasu pracy (praca z biura we Wrocławiu 1 raz na 2 tygodnie) Udział w rozwoju globalnego produktu technologicznego Pracę w międzynarodowym środowisku Realny wpływ na rozwój systemu oraz decyzje technologiczne Stabilny, długoterminowy projekt produktowy Kartę Multisport Pracę w zespole nastawionym na współpracę i dzielenie się wiedzą

🏢 Summary: Senior Full Stack Team Lead role focused on building and scaling web applications using React and Node.js while leading a development team. The position combines hands-on front-end and back-end development with architecture design, API development, and deployment in cloud environments. You will drive technical decisions, ensure code quality, and oversee delivery of scalable, production-ready systems. 🗂️ Requirements: 7+ years full-stack development experience with React and Node.js, 2+ years experience in leadership or senior technical role, Strong experience with React.js, Redux, React Hooks, Strong knowledge of HTML5, CSS3, modern JavaScript, Proficiency in Node.js and Express.js, Experience building REST APIs, Experience with PostgreSQL or MySQL, Experience with authentication methods (OAuth, JWT, sessions), Experience with CI/CD and Docker, Experience working with production systems, Experience with Git, Understanding of Agile/Scrum methodologies 📃 Skills: React, Redux, JavaScript, HTML5, CSS3, Node.js, Express, REST, GraphQL, PostgreSQL, MySQL, OAuth, JWT, Docker, Kubernetes, AWS, Azure, GCP, Git, CI/CD, Webpack, Babel, Vite, MongoDB 🏢 Description: Overview We are a leading company in AI-based enterprise operations. We provide digital solutions and consulting services that help businesses grow and improve. We use modern technology to make processes simpler, increase efficiency, and create new ways to earn money, especially in private capital markets. Our ecosystem includes three main parts. First, PaaS (Platform as a Service) with the Orion Platform, which helps improve workflows, show useful insights, and support value growth across portfolios. Second, SaaS (Software as a Service), a cloud platform that offers strong performance and smart tools at scale. Third, our Solutions and Consulting Suite, which includes flexible technology solutions to manage, grow, and improve company performance. With more than 10 years of experience, we support fast-growing companies and private equity platforms, turning technology into a real business advantage. Responsibilities and Duties We are looking for an experienced Full Stack Team Lead with strong skills in React and Node.js. The right person has over 7 years of experience building high-quality web applications and has experience leading a team. You will guide developers, work on both front-end and back-end, take part in all stages of development, and support junior team members. Key Responsibilities Team Leadership & Mentorship: Lead and support a team of developers. Help them grow, review code, and give technical advice. Front-End Development: Build and maintain user interfaces using React.js, Redux, and modern JavaScript. Back-End Development: Create strong and scalable server applications and APIs using Node.js and Express. Integration: Work with database engineers to design databases and manage data using MongoDB or SQL. Application Architecture: Design scalable systems and microservices that meet business needs. Testing & Debugging: Write tests, fix issues, and improve performance. Support good testing practices. Deployment: Manage releases using CI/CD tools and Docker. Collaboration: Work with designers, product managers, and developers to create useful solutions. Communicate with both technical and non-technical teams. Maintenance: Monitor systems, fix problems, and improve applications. Documentation: Write and maintain technical documents for systems and APIs. Requirements Front-End: Strong experience with React.js, Redux, React Hooks, and component-based design Good knowledge of HTML5, CSS3, and modern JavaScript Familiar with tools like Webpack, Babel, or Vite Back-End: Strong skills in Node.js and Express.js Experience building and using APIs (GraphQL is a plus, REST is required) Knowledge of authentication methods like OAuth, JWT, and sessions Database: Experience with PostgreSQL or MySQL Additional Skills: Experience with Docker and Kubernetes is a plus Knowledge of cloud platforms like AWS, Azure, or GCP Experience with Git Understanding of Agile/Scrum methods Qualifications At least 7 years of experience in full-stack development with React and Node.js At least 2 years in a leadership or senior role Experience working with live production systems Bachelor’s degree in Computer Science or similar (preferred) Soft Skills Strong problem-solving and analytical thinking Good communication and teamwork skills Ability to work independently and manage tasks well Willingness to learn new technologies and improve continuously Why Join Us? We look for people who solve problems creatively, learn quickly, and enjoy working in an open and diverse team. We work hard, but we also like to enjoy what we do and aim for high results.

🏢 Summary: The offer is for a Senior Frontend Developer responsible for building and maintaining user interfaces using React within AI-powered business platforms. The role focuses on developing high-quality, scalable front-end solutions with strong emphasis on TDD, performance, and cross-team collaboration. Candidates will work in an Agile environment delivering robust, user-friendly products. 🗂️ Requirements: 6+ years of experience with JavaScript and TypeScript, Strong knowledge of React.js and Redux, Understanding of JavaScript design patterns, Knowledge of functional programming, Knowledge of asynchronous programming, Experience with Git and branch management, Ability to debug front-end issues using debugging tools, Experience creating and integrating custom packages, Understanding of object-oriented programming in JavaScript, Hands-on experience with HTML5 and CSS3, Experience with Test-Driven Development (TDD), Experience with Continuous Integration, Familiarity with Agile development practices, Ability to write cross-browser compatible code 📃 Skills: JavaScript, TypeScript, React, Redux, Next.js, HTML5, CSS3, Git, TDD, CI, Agile 🏢 Description: Overview We are a company that leads in AI-powered business operations, providing digital solutions and consulting services that help businesses grow and improve. We focus on using advanced technology to make operations easier, increase efficiency, and create new opportunities, especially in private capital markets. Our services include: PaaS (Platform as a Service): Our main platform uses AI to improve workflows, generate insights, and help businesses grow faster. SaaS (Software as a Service): A cloud platform that offers strong performance, smart tools, and large-scale execution. S&C (Solutions and Consulting Suite): Flexible technology tools to manage, develop, and improve business performance. With over ten years of experience helping fast-growing companies and private equity-backed businesses, we bring deep knowledge and a proven track record of turning technology into a real advantage. Responsibilities Design and develop user interfaces using React. Implement and maintain test-driven development (TDD) and continuous integration. Work with project managers, analysts, and sales teams to deliver high-quality products on time. Follow best practices in testing, accessibility, and performance. Work closely with design, backend, QA, and product teams to build user-friendly solutions. Requirements 6+ years experience with JavaScript and TypeScript. Understand design patterns and how to use them in JavaScript. Experience with modern front-end frameworks like React.js + Redux; Next.js is a bonus. Knowledge of functional and asynchronous programming. Experience with Git and branch management. Ability to debug front-end issues and use debugging tools. Familiar with creating and integrating custom packages. Understand object-oriented programming concepts in JavaScript. Can work under pressure and meet tight deadlines. Hands-on experience with HTML5 and CSS3. Familiar with Agile development practices. Good communication and organizational skills. Able to write code that works across different browsers. Bachelor’s degree in Computer Science or similar is preferred. Why Join Us? We appreciate creative problem-solvers who learn quickly, work well in a diverse environment, and like to raise the standard for success. We work hard but also make sure to enjoy what we do.

🏢 Summary: B2B contract for a senior backend-focused engineer to design and develop scalable APIs and services using Ruby on Rails, with supporting frontend work in React. The role involves building production-grade systems, ensuring high test coverage, and improving performance, reliability, and scalability in a distributed environment. 🗂️ Requirements: 6+ years commercial experience with Ruby on Rails, Experience building production APIs and backend systems, Entry-level experience with React (components, state management, API integration), Knowledge of PostgreSQL and relational databases, Experience with RSpec and automated testing, Experience with AWS and/or Heroku, Understanding of scalable and distributed systems, Experience working in Agile teams, English and Polish at minimum B2+ 📃 Skills: Ruby, Rails, React, PostgreSQL, SQL, RSpec, AWS, Heroku, API, REST, JavaScript, 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 and develop backend features and APIs using Ruby on Rails as the primary technology stack. Contribute to frontend development in React, including building components and integrating APIs when needed. Build scalable backend services and APIs powering applications. Develop reusable frontend components and maintain a clean UI architecture. Collaborate directly with Product, Design, QA, and DevOps teams to deliver business-focused solutions. Improve application performance, reliability, scalability, and maintainability. Write clean, production-grade code with strong test coverage (unit, integration, E2E). Review code, maintain engineering standards, and support technical decision-making. Troubleshoot production issues and support stable deployments. Participate in agile delivery processes and contribute to continuous improvement. Support knowledge sharing and technical mentorship within the team. Requirements: 6+ years of commercial Ruby on Rails experience. Solid entry-level React experience (components, state management, API integration). Strong experience building production APIs and backend systems. Good knowledge of PostgreSQL and relational databases. Experience with RSpec, automated testing, and strong engineering practices. Experience with AWS and/or Heroku. Understanding of scalable and distributed systems. Experience working in Agile teams. Strong communication skills in English at a minimum B2+ level. Nice to Have: Tech Lead or mentoring experience. Experience with observability, monitoring, and performance optimization. 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 Ruby on Rails Developer responsible for building and maintaining production-grade server-side applications, implementing new features, and ensuring high code quality through testing and reviews. The role involves working with AWS-based environments, optimizing performance and scalability, and contributing to frontend components in React. The position requires close collaboration with cross-functional teams in a remote or hybrid setup. 🗂️ Requirements: 6+ years of experience with Ruby on Rails, Experience with Active Record and RSpec, Experience with AWS or Heroku in production environments, Experience with PostgreSQL or other RDBMS, Experience writing unit, integration, and E2E tests, Experience with TDD or strong testing practices, Experience building applications using MVC pattern, Experience building React components and integrating APIs, Understanding of distributed systems, Experience designing and consuming REST APIs, Knowledge of Agile methodologies (Scrum or Kanban), Polish and English at minimum B2 level 📃 Skills: Ruby, Rails, ActiveRecord, RSpec, AWS, Heroku, PostgreSQL, RDBMS, React, REST, MVC, TDD, Scrum, Kanban 🏢 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: Implementing new functionalities on our client’s platform. Solving complex programming challenges while improving your knowledge. Conducting regular code reviews / PR reviews for your colleagues. Maintaining existing code and fixing bugs. Writing unit, integration, and E2E tests. Contributing to frontend components using React when needed. Supporting rapid iteration, experimentation, and data-driven development initiatives. Optimizing application performance, reliability, and scalability. Collaborating with Product Managers and cross-functional teams to align engineering execution with product vision. Requirements: 6+ years of experience in Ruby on Rails. Familiarity with Active Record and RSpec. Experience working on production applications in AWS or Heroku. Experience working with RDBMS like PostgreSQL. Experience writing tests / following a TDD approach or strong testing culture. Experience building server-side applications using the MVC pattern or similar. React experience (building components, integrating APIs). Understanding distributed systems and resilient applications. Practical knowledge of REST API communication. Polish and English at B2+ minimum level. Familiarity with Agile methodologies (Scrum, Kanban). Experience as a tech team lead is a strong plus. Demonstrated ability to leverage AI tools to improve workflows or development efficiency is a plus. 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: B2B contract for a Senior Ruby on Rails Developer to build and enhance a client platform, focusing on backend development, testing, performance optimization, and occasional React frontend work. The role involves solving complex engineering challenges, conducting code reviews, and collaborating with cross-functional teams in a remote-first environment. Emphasis is placed on scalable, reliable systems and data-driven product development. 🗂️ Requirements: 5+ years Ruby on Rails experience, Strong knowledge of ActiveRecord, Experience with RSpec, Experience with AWS or Heroku in production, Experience with PostgreSQL or other RDBMS, Experience with TDD and automated testing, Experience building MVC-based server-side applications, Experience building React components and integrating APIs, Understanding of distributed systems, Practical knowledge of REST APIs, B2+ level Polish and English, Experience with Agile methodologies 📃 Skills: Ruby, Rails, ActiveRecord, RSpec, AWS, Heroku, PostgreSQL, RDBMS, TDD, MVC, React, REST, Scrum, Kanban 🏢 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: Implementing new functionalities on our client’s platform. Solving complex programming challenges while improving your knowledge. Conducting regular code reviews / PR reviews for your colleagues. Maintaining existing code and fixing bugs. Writing unit, integration, and E2E tests. Contributing to frontend components using React when needed. Supporting rapid iteration, experimentation, and data-driven development initiatives. Optimizing application performance, reliability, and scalability. Collaborating with Product Managers and cross-functional teams to align engineering execution with product vision. Requirements: 5+ years of experience in Ruby on Rails. Familiarity with Active Record and RSpec. Experience working on production applications in AWS or Heroku. Experience working with RDBMS like PostgreSQL. Experience writing tests / following a TDD approach or strong testing culture. Experience building server-side applications using the MVC pattern or similar. React experience (building components, integrating APIs). Understanding distributed systems and resilient applications. Practical knowledge of REST API communication. Polish and English at B2+ minimum level. Familiarity with Agile methodologies (Scrum, Kanban). Experience as a tech team lead is a strong plus. Demonstrated ability to leverage AI tools to improve workflows or development efficiency is a plus. 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.