Expert Fullstack .NET & TS developer

🏢 Summary: Mid/Senior Fullstack .NET Developer role on a long-term fintech project for the Scandinavian market, focused primarily on backend development with additional frontend and architectural responsibilities. The position involves working with a modern cloud-native, microservices-based platform using .NET, React, and AWS. Developers actively contribute to technical decisions, architecture, and product evolution in a collaborative environment. 🗂️ Requirements: 5+ years of experience as a .NET Developer, Strong proficiency in C#, Experience with TypeScript, Fullstack experience with React, NestJS, NextJS, Experience building Web APIs and backend services, Understanding of multithreading and parallelism, Experience with Entity Framework and/or Dapper, Experience with unit testing and mocking, Knowledge of microservices architecture, Knowledge of event-driven architecture, Experience with Git, Experience with CI/CD workflows, Experience with GitHub, Experience with SQL and NoSQL databases, Experience with PostgreSQL, MongoDB, Redis, Experience with .NET 6 or newer, Experience with AWS, English proficiency B2+/C1 📃 Skills: .NET, C#, TypeScript, React, NestJS, NextJS, Node.js, WebAPI, EntityFramework, Dapper, Microservices, Kafka, Git, GitHub, CI/CD, PostgreSQL, MongoDB, Redis, AWS, SQL, NoSQL, Playwright 🏢 Description: Join KOIA and work on a modern fintech platform built for the Scandinavian market. We are looking for a Mid/Senior Fullstack .NET Developer to join a long-term project for our Norwegian client. The role is backend-heavy (~65%), with additional involvement in architecture, technical analysis, and frontend development using React and TypeScript. You’ll work in a collaborative engineering environment where developers actively influence technical decisions, architecture, and product evolution. Project The application is built using modern technologies and cloud-native architecture. Frontend: React, TypeScript z NestJS, NextJS Backend: .NET and Node.js Infrastructure: AWS Architecture: Microservices, Event-driven architecture (Kafka) Testing: Unit tests, Integration/Process tests (test containers based), E2E Tests (Playwright) Databases: PostgreSQL, MongoDB, Redis Cloud: AWS CI/CD: GitHub Actions The team focuses strongly on: code quality, automated testing, maintainability, minimizing technical debt, continuous improvement. Regular technical and architectural discussions are part of the development process, and every team member is encouraged to propose ideas and improvements. Your Responsibilities: Collaborate on both the back-end and front-end development of applications. Assist clients in transforming their existing applications to a new tech stack. Work in a remote-first environment with an expectation to join the team from our Gdańsk office 2 days per week. Contribute to the success of cutting-edge technology projects. Maintain a client-focused approach and engage in frequent communication with clients. Pay attention to detail and ensure the quality of development work. Your qualifications: Must-have 5+ years of experience as a .NET Developer with TypeScript Excellent development skills in C# Fullstack experience with React, NestJS, NextJS Experience building Web APIs and backend services Good understanding of multithreading and parallelism Experience with Entity Framework and/or Dapper Experience with unit testing and mocking Good understanding of Microservice architecture, Event-driven architecture Git The entire CI/CD workflow from development to release GitHub SQL and noSQL databases (preferably with PostgreSQL, MongoDB, Redis) .NET 6 or newer AWS Very good English communication skills (B2+/C1) Experience using tools such as Claude, Copilot or Cursor in daily development Ability to leverage LLM-based tools for debugging, testing and development acceleration Actively experiments with modern AI-assisted development workflows Nice-to-have Experience with Node.js Knowledge of Domain-Driven Design (DDD) Experience with event-driven systems Fintech or product-company background Bachelor's degree in computer science or related studies What We Value Ownership and accountability Strong communication and collaboration skills Curiosity and a continuous learning mindset Proactive approach to problem-solving Attention to detail and code quality Openness to feedback and improvement Not being afraid to take the initiative to get work done while suggesting changes and improvements where needed. What We Offer Competitive Compensation 27-32 EUR/h + paid days off (B2B) An alternative higher-rate option is available without paid leave Remote-first culture with regular in-person collaboration. Impact & Autonomy You’ll have real influence on technical decisions, architecture, and product development. Learning & Growth Mentorship opportunities Self-development days Access to learning resources and tools Healthy Work Environment We value sustainable work, mature communication, and work-life balance over overtime culture. Office Space in Gdańsk Our office offers: adjustable desks, bike parking, fully stocked kitchen. Open space and smaller rooms Meaningful Projects You’ll work with innovative companies from the fintech and climate-tech sectors across Scandinavia. Recruitment Process At KOIA, we value a clear and efficient recruitment journey. Here’s what to expect: Email with Clarifying Questions After submitting your application, you’ll receive an email with a few additional questions to better understand your experience and skills. Video Call with HR A 1-hour conversation with our HR team to discuss your background, expectations, and company culture fit. Technical Video Call A technical discussion with our engineers focused on architecture, problem-solving, and real-world scenarios. You’ll walk through how you approach technical challenges, explain past decisions, and reason about solutions. No live coding. Offer If everything aligns, you’ll receive a job offer and details about the next steps to join KOIA!

🏢 Summary: Mid-level Full-stack Developer role focused on building and maintaining web and mobile applications using React and .NET technologies. The position involves developing scalable backend services, microservices, and SEO-friendly frontends integrated with CMS, within a multinational Agile environment. The role combines frontend, backend, cloud, and DevOps responsibilities with regular team collaboration. 🗂️ Requirements: 2–4 years experience as FullStack Developer, .NET 8/10 proficiency, C# proficiency, Strong React knowledge, JavaScript proficiency, TypeScript proficiency, HTML5 knowledge, CSS3 knowledge, Experience with RESTful APIs, Experience with Git, Experience with Microsoft Azure (Functions, Durable Functions, CosmosDB, ServiceBus, Application Insights), Experience with CI/CD pipelines, Experience with Agile methodologies, Communicative English (B2+) 📃 Skills: .NET, C#, React, JavaScript, TypeScript, HTML5, CSS3, REST, Git, Azure, Functions, CosmosDB, ServiceBus, ApplicationInsights, CI/CD, ReactNative, Expo, Sanity, GROQ, Redux, RxJS, Tanstack, Sentry, Firebase, Analytics 🏢 Description: Join Our Team as a Full-stack Developer (React, C#)! We are seeking a talented Mid FullStack Developer proficient in .NET and React to join our team. As part of our company culture, we value collaboration and regular in-person interactions. Our team meets every two months in our Poznań office for informal gatherings to connect, share ideas, and strengthen teamwork in a relaxed setting. You will work in multinational environment and will be responsible for designing and implementing software solutions, utilizing both front-end and back-end technologies. This role requires strong problem-solving skills, excellent communication abilities, and a passion for delivering high-quality code. Ready to take the next step in your career? Apply now and join us! Key Responsibilities: • Design and develop SEO-friendly web application, based on React and TypeScript and integrated with Sanity CMS. • Contributing to a mobile application using React Native, TypeScript and Expo . • Build and maintain microservices to enhance the web experience, including features like roadside assistance, car repair bookings, and membership management. • Develop robust and scalable backend systems using .NET 8/10, Azure ServiceBus, Functions, CosmosDB and more. • Utilize Sentry for error monitoring and Google Analytics/Firebase to track user behaviour and optimize performance. Requirements : Proven experience (2-4 years) as a FullStack Developer Proficiency in .NET (preferably .NET 8/10), C# Strong understanding of front-end technologies, including React, JavaScript, TypeScript, HTML5, and CSS3 Practical knowledge of clean-code principles and patterns, drive to write clean, testable and maintainable code Experience with RESTful APIs and Web Services Knowledge of version control systems, such as Git Excellent problem-solving and analytical skills Familiarity with Microsoft Azure platform (Functions and Durable Functions, CosmosDb, ServiceBus, Application Insights) Experience with DevOps approach and CI/CD pipelines Strong communication and interpersonal skills, communicative English (B2+) Experience with Agile development methodologies Nice to have: Experience in working with Sanity CMS and GROQ query language (or any other headless CMS) Familiarity with Figma or similar tools At least basic knowledge about Server Side Rendering and libraries like: Redux, RxJS, Tanstack Experience in working with mobile apps and practical knowledge of React Native, Expo, Expo Application Services Knowledge of microservices architecture and software integration patterns We offer: Conference/workshop budget of approximately 10000 PLN!- the budget renews every year and can be used for conferences, workshops, training programs, certifications, studies, or other development initiatives. "Fabresikowe": one-time 1000 PLN bonus to create your work space more comfortable and more tailored to your needs! Relaxing office massages In-house trainings Team events Frequent company events Free breakfast every day Free beverages, fresh fruit, snacks Chill out room English and Norwegian classes

🏢 Summary: Mid-Level Fullstack .NET Developer role focused on building and maintaining scalable, microservice-based web applications in the online banking domain. The position involves developing REST APIs, implementing automated testing, and contributing to CI/CD processes within a hybrid work model. You will work with modern .NET and Angular technologies to deliver high-quality, robust systems. 🗂️ Requirements: Minimum 3 years of full stack development experience, Strong knowledge of C# and .NET Core, Practical experience with Angular, Experience with REST API development, Experience with microservice architecture, Hands-on experience with Docker and Kubernetes, Experience with automated testing (unit and E2E), Knowledge of SOLID principles and design patterns, Experience with MS SQL and PostgreSQL, Familiarity with CI/CD pipelines and SSDLC, Experience with Git-based version control, Good command of Polish, Legal right to work in the EU 📃 Skills: C#, .NET, Angular, REST, Microservices, Docker, Kubernetes, MSSQL, PostgreSQL, Git, Jenkins, TeamCity, JIRA, CI/CD, SSDLC 🏢 Description: Ignite the future of digital innovation — shape powerful, scalable systems with cutting-edge technologies! Warsaw-based opportunity with hybrid work model (2 days in the office / month). As a Mid-Level Fullstack .NET Developer , you will be working for our client, a leader in the online banking industry dedicated to delivering innovative solutions. Your expertise will contribute to designing and implementing robust, microservice-based systems, empowering businesses to thrive in a digital landscape. Join us and be part of a dynamic environment where your skills fuel impactful projects and career growth. Your main responsibilities: Develop and maintain scalable web applications using .NET Core, C#, and Angular. Write automated unit and E2E tests to ensure high-quality deliverables. Apply SOLID principles, design patterns, IoC, and DI to create maintainable code. Design and implement REST APIs within microservice architecture. Collaborate with cross-functional teams utilizing JIRA, TeamCity, Jenkins, and version control systems like git/bitbucket. Support and optimize database interactions with MSSQL and PostgreSQL. Participate in continuous integration and delivery processes (SSDLC, CI/CD tools). You're ideal for this role if you have: Minimum of 3 years of professional experience in full stack development. Practical knowledge of C#, .NET Core, Angular. Hands-on experience with Docker and Kubernetes. Experience with automated testing, SOLID principles, design patterns, and REST API development. Familiarity with MS SQL, PostgreSQL, and microservice architecture. Knowledge of SSDLC, CI/CD pipelines, and tools such as JIRA, TeamCity, Jenkins, and git. It is a strong plus if you have: (optional) Experience with cloud platforms like Azure or AWS. Certifications in microservices or cloud technologies. Language required for the role: Good command of Polish. Eligibility to work in Europe: 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: Mid-Level Fullstack .NET Developer role focused on building and maintaining scalable web applications within a microservices architecture. The position involves developing robust REST APIs, implementing automated testing, and contributing to CI/CD processes in a hybrid work model. You will work with modern .NET and Angular technologies to deliver high-quality, enterprise-grade systems. 🗂️ Requirements: Minimum 3 years of full stack development experience, Strong knowledge of C# and .NET Core, Practical experience with Angular, Experience with REST API development, Experience with microservice architecture, Experience with automated testing (unit, E2E), Knowledge of SOLID principles and design patterns, Experience with Docker and Kubernetes, Experience with MSSQL and PostgreSQL, Experience with CI/CD pipelines and related tools, Familiarity with JIRA, TeamCity, Jenkins, git, Communicative Polish, Legal right to work in the EU 📃 Skills: C#, .NET, Angular, REST, Microservices, Docker, Kubernetes, MSSQL, PostgreSQL, Git, Jenkins, TeamCity, JIRA, CI/CD, SOLID 🏢 Description: Ignite the Future of Digital Innovation — Shape Powerful, Scalable Systems with Cutting-Edge Technologies! Warszawa-based opportunity with hybrid work model (up to 4 days remote per week). As a Mid-Level Fullstack .NET Developer , you will be working for our client, a forward-thinking leader in the software industry dedicated to delivering innovative solutions. Your expertise will contribute to designing and implementing robust, microservice-based systems, empowering businesses to thrive in a digital landscape. Join us and be part of a dynamic environment where your skills fuel impactful projects and career growth. Your main responsibilities: Develop and maintain scalable web applications using .NET Core, C#, and Angular. Write automated unit and E2E tests to ensure high-quality deliverables. Apply SOLID principles, design patterns, IoC, and DI to create maintainable code. Design and implement REST APIs within microservice architecture. Collaborate with cross-functional teams utilizing JIRA, TeamCity, Jenkins, and version control systems like git/bitbucket. Support and optimize database interactions with MSSQL and PostgreSQL. Participate in continuous integration and delivery processes (SSDLC, CI/CD tools). You're ideal for this role if you have: Minimum of 3 years of professional experience in full stack development. Practical knowledge of C#, .NET Core, Angular. Experience with Docker and Kubernetes. Experience with automated testing, SOLID, design patterns, and REST API development. Familiarity with MS SQL, PostgreSQL, and microservice architecture. Knowledge of SSDLC, CI/CD pipelines, and tools such as JIRA, TeamCity, Jenkins, and git. It is a strong plus if you have: (optional) Certifications in cloud technologies or microservice architectures. Language Required for the role: Polish (Communicative level) 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 in English or Polish, along with a statement confirming your consent to the processing and storage of your personal data.

🏢 Summary: Hybrid Fullstack Developer role focused on building and maintaining scalable web applications using Java and React.js. The position involves designing backend services and RESTful APIs, developing modern frontend interfaces, and contributing to CI/CD and DevOps practices. Work includes testing, performance optimization, and collaboration on architecture and microservices. 🗂️ Requirements: Strong experience with Java and Spring Boot, Solid experience with React.js and state management, Experience designing and consuming RESTful APIs, Experience with microservices architecture, Proficiency in JavaScript, HTML5, CSS3, Experience with relational or NoSQL databases, Knowledge of unit and integration testing practices, Experience with CI/CD pipelines, Familiarity with Git and version control workflows, Ability to work with Agile/Scrum methodologies 📃 Skills: Java, Spring, SpringBoot, React, Redux, JavaScript, HTML5, CSS3, Webpack, Babel, ESLint, JUnit, Mockito, Jest, MySQL, PostgreSQL, NoSQL, Git, CI/CD, Docker, Kubernetes, AWS, Azure, GCP, Kafka, GraphQL, WebSocket 🏢 Description: We are looking for a highly skilled Fullstack Developer with expertise in Java and React.js to join our Kraków-based development team. You will design, develop, and maintain scalable, high-performance web applications, contributing to both backend services and rich frontend interfaces. This role follows a hybrid working model , with 2–3 days per week onsite in Kraków. Key Responsibilities Backend Development: Architect, implement, and maintain backend services using Java , Spring Boot , and related frameworks Frontend Development: Build responsive, modular, and maintainable React.js applications with a focus on component-driven design Design and implement RESTful APIs and microservices , ensuring high performance, security, and scalability Collaborate with cross-functional teams to define technical requirements , system architecture, and feature implementation Apply unit testing, integration testing, and end-to-end testing best practices (JUnit, Mockito, Jest, React Testing Library) Participate in code reviews , enforce coding standards, and promote best practices in clean code, SOLID principles, and design patterns Troubleshoot and optimize application performance and resolve production issues Manage CI/CD pipelines , automate deployments, and support DevOps practices Stay up-to-date with emerging technologies and frameworks to continuously improve application architecture Required Skills and Experience Strong experience with Java , Spring Boot , and related backend frameworks Solid experience with React.js , Redux , or state management libraries Proven experience in designing and consuming RESTful APIs and microservices architecture Proficient in JavaScript, HTML5, CSS3, and modern frontend tooling (Webpack, Babel, ESLint) Experience with relational databases (MySQL, PostgreSQL) and/or NoSQL databases Familiarity with Git , version control workflows, and Agile/Scrum methodologies Understanding of unit testing, integration testing, and test-driven development (TDD) Good problem-solving and communication skills in English Nice to Have Experience with TypeScript and advanced React patterns (Hooks, Context API, Suspense) Knowledge of Docker , Kubernetes , or cloud platforms (AWS, Azure, GCP) Experience with event-driven architectures , message queues , or Kafka Familiarity with GraphQL or WebSocket-based real-time applications

🏢 Summary: Long-term hybrid Fullstack .NET Developer role focused on developing and modernizing complex systems, including monolithic applications and WPF components, while building new features with ASP.NET Core and React. The position involves fullstack development, refactoring legacy systems, and ensuring performance, scalability, and code quality in an international environment. 🗂️ Requirements: Minimum 6 years experience as .NET/Fullstack Developer, Strong hands-on experience with C#, Strong hands-on experience with ASP.NET Core, Strong hands-on experience with React, Experience with JavaScript, Experience with monolithic architecture, Experience in refactoring legacy systems, Experience with WPF or willingness to maintain WPF components, English level B2 or higher, Fluent Polish, Residence in Poland 📃 Skills: C#, ASP.NET, ASP.NETCore, React, JavaScript, WPF, .NET, SQL 🏢 Description: Poszukujemy doświadczonego Fullstack .NET Developera z silnymi umiejętnościami React, który dołączy do długoterminowego projektu realizowanego przez Sii dla międzynarodowej organizacji znanej z zaawansowanych technologii laboratoryjnych i diagnostycznych. Będziesz pracował nad rozwojem i modernizacją złożonych systemów, w tym starszych aplikacji monolitycznych i komponentów WPF, jednocześnie przyczyniając się do tworzenia nowych funkcji opartych na ASP.NET Core i nowoczesnych frameworkach JavaScript. Rola jest hybrydowa, z 2-3 dniami w tygodniu w naszym biurze we Wrocławiu. Jeśli jesteś gotowy na kolejne duże wyzwanie - aplikuj już teraz! Twoje zadania Projektowanie, rozwijanie i utrzymywanie aplikacji fullstack .NET Developer przy użyciu ASP.NET Core, C# i React. Modernizacja i refaktoryzacja istniejących systemów monolitycznych, zapewnienie wydajności i skalowalności Wdrażanie i ulepszanie komponentów interfejsu użytkownika, w tym w razie potrzeby praca z WPF Współpraca z wielofunkcyjnymi zespołami w zakresie architektury, przeglądów kodu i kierunku technicznego Rozwiązywanie problemów, optymalizacja i zapewnianie wysokiej jakości, testowalnego i łatwego w utrzymaniu kodu Wymagania Co najmniej 6 lat doświadczenia jako .NET/Fullstack Developer Silne praktyczne doświadczenie z C#, ASP.NET Core i React/JavaScript Znajomość monolitycznych architektur i podejścia do refaktoryzacji Doświadczenie z WPF lub chęć utrzymania istniejących komponentów desktopowych Bardzo dobra znajomość języka angielskiego (B2+) umożliwiająca codzienną komunikację w międzynarodowym środowisku Wymagana biegła znajomość języka polskiego Wymagane miejsce zamieszkania w Polsce Benefity, które czekają na Ciebie: Tytuł Great Place to Work od 2015 roku - to dzięki opiniom pracowników otrzymujemy tytuł i wdrażamy nowe pomysły Stabilność zatrudnienia - 2,1 MLD PLN przychodu, brak długów, od 2006 roku na rynku Dzielimy się zyskiem z pracownikami - od 2022 roku przeznaczyliśmy na ten cel już ponad 76 milionów PLN Bogaty pakiet benefitów - prywatna opieka zdrowotna, platforma kafeteryjna, zniżki na samochody i więcej Komfortowe miejsce pracy - pracuj w naszych biurach klasy A lub zdalnie Dziesiątki fascynujących projektów dla prestiżowych marek z całego świata 1 000 000 PLN rocznie na Twoje pomysły - taką kwotą wspieramy pasje i akcje wolontariackie naszych pracowników Stawiamy na Twój rozwój - meetupy, webinary, platforma szkoleniowa i blog technologiczny – Ty wybierasz Fantastyczna atmosfera stworzona przez wszystkich Sii Power People Dołącz do zespołu Sii – rozwijaj umiejętności, zdobywaj doświadczenie i buduj karierę!

🏢 Summary: Long-term hybrid role for an experienced Fullstack .NET Developer to develop and modernize complex systems using ASP.NET Core and React, including refactoring monolithic applications and maintaining WPF components. The position involves building new features, improving performance and scalability, and ensuring high-quality, maintainable code in an international environment. 🗂️ Requirements: Minimum 6 years of experience as .NET/Fullstack Developer, Strong hands-on experience with C#, Strong hands-on experience with ASP.NET Core, Strong hands-on experience with React, Experience with JavaScript, Knowledge of monolithic architectures, Experience in refactoring legacy systems, Experience with WPF or willingness to maintain WPF components, English level B2+, Fluent Polish, Residence in Poland 📃 Skills: C#, ASP.NET, ASP.NETCore, React, JavaScript, WPF, .NET 🏢 Description: Poszukujemy doświadczonego Fullstack .NET Developera z silnymi umiejętnościami React, który dołączy do długoterminowego projektu realizowanego przez Sii dla międzynarodowej organizacji znanej z zaawansowanych technologii laboratoryjnych i diagnostycznych. Będziesz pracował nad rozwojem i modernizacją złożonych systemów, w tym starszych aplikacji monolitycznych i komponentów WPF, jednocześnie przyczyniając się do tworzenia nowych funkcji opartych na ASP.NET Core i nowoczesnych frameworkach JavaScript. Rola jest hybrydowa, z 2-3 dniami w tygodniu w naszym biurze we Wrocławiu. Jeśli jesteś gotowy na kolejne duże wyzwanie - aplikuj już teraz! Twoje zadania Projektowanie, rozwijanie i utrzymywanie aplikacji fullstack .NET Developer przy użyciu ASP.NET Core, C# i React. Modernizacja i refaktoryzacja istniejących systemów monolitycznych, zapewnienie wydajności i skalowalności Wdrażanie i ulepszanie komponentów interfejsu użytkownika, w tym w razie potrzeby praca z WPF Współpraca z wielofunkcyjnymi zespołami w zakresie architektury, przeglądów kodu i kierunku technicznego Rozwiązywanie problemów, optymalizacja i zapewnianie wysokiej jakości, testowalnego i łatwego w utrzymaniu kodu Wymagania Co najmniej 6 lat doświadczenia jako .NET/Fullstack Developer Silne praktyczne doświadczenie z C#, ASP.NET Core i React/JavaScript Znajomość monolitycznych architektur i podejścia do refaktoryzacji Doświadczenie z WPF lub chęć utrzymania istniejących komponentów desktopowych Bardzo dobra znajomość języka angielskiego (B2+) umożliwiająca codzienną komunikację w międzynarodowym środowisku Wymagana biegła znajomość języka polskiego Wymagane miejsce zamieszkania w Polsce Benefity, które czekają na Ciebie: Tytuł Great Place to Work od 2015 roku - to dzięki opiniom pracowników otrzymujemy tytuł i wdrażamy nowe pomysły Stabilność zatrudnienia - 2,1 MLD PLN przychodu, brak długów, od 2006 roku na rynku Dzielimy się zyskiem z pracownikami - od 2022 roku przeznaczyliśmy na ten cel już ponad 76 milionów PLN Bogaty pakiet benefitów - prywatna opieka zdrowotna, platforma kafeteryjna, zniżki na samochody i więcej Komfortowe miejsce pracy - pracuj w naszych biurach klasy A lub zdalnie Dziesiątki fascynujących projektów dla prestiżowych marek z całego świata 1 000 000 PLN rocznie na Twoje pomysły - taką kwotą wspieramy pasje i akcje wolontariackie naszych pracowników Stawiamy na Twój rozwój - meetupy, webinary, platforma szkoleniowa i blog technologiczny – Ty wybierasz Fantastyczna atmosfera stworzona przez wszystkich Sii Power People Dołącz do zespołu Sii – rozwijaj umiejętności, zdobywaj doświadczenie i buduj karierę!

🏢 Summary: Senior Fullstack .NET Developer role focused on modernizing a legacy business process management platform within a digital banking environment. The position involves rebuilding applications from .NET Framework to modern .NET, developing React frontend components, and deploying scalable solutions to Kubernetes. You will contribute to system design, automated testing, and AI-assisted development in an enterprise Agile setup. 🗂️ Requirements: 5+ years of experience with C# and .NET, Experience modernizing legacy applications from .NET Framework, Strong knowledge of React, Practical experience with LLM tools (Claude, Codex), Experience with automated testing, Hands-on experience with Docker and Kubernetes, Experience designing and implementing enterprise applications, Strong knowledge of MS SQL, Experience with Git, JIRA, and TeamCity 📃 Skills: CSharp, DotNet, DotNetFramework, React, Kubernetes, Docker, MSSQL, Git, JIRA, TeamCity, Claude, Codex, Agile 🏢 Description: Unleash innovative web solutions — shape the future of digital banking experiences! Łódź-based opportunity with hybrid work model (2 days in the office/month). As a Senior Fullstack .NET React Developer , you will be working for our client, a leading financial institution focused on delivering innovative digital banking solutions. You will join a strategic modernization initiative involving the redevelopment of a business process management platform. The project focuses on rebuilding legacy applications from .NET Framework to modern .NET technologies, migrating infrastructure from on-premises environments to Kubernetes, and implementing high-quality engineering practices. You will collaborate closely with AI-powered development tools, contribute to system design decisions, and help deliver scalable, secure, and maintainable solutions in a complex enterprise environment. Your main responsibilities: Develop and maintain backend services using .NET and C# Rebuild legacy applications from .NET Framework to modern .NET architecture Design and implement frontend components using React Create and maintain automated unit and regression tests Collaborate with business stakeholders to analyze and refine requirements Design scalable and maintainable software solutions Integrate applications with databases and external services Utilize LLM-based tools such as Claude and Codex to support software development activities Participate in code reviews and ensure adherence to development standards Deploy and support applications running in Kubernetes environments Work closely with cross-functional teams in an Agile delivery model You're ideal for this role if you have: At least 5 years of experience in software development using C# and .NET Experience with .NET Framework and modernizing legacy code Good knowledge of React Practical experience working with LLM tools such as Claude and Codex Strong experience with automated testing Hands on experience with Docker and Kubernetes Experience designing and implementing enterprise applications Strong knowledge of MS SQL Experience using Git, JIRA, and TeamCity Ability to work independently while collaborating effectively within a team English skills sufficient to write and understand technical documentation Nice to have: Knowledge of message brokers, especially RabbitMQ,

🏢 Summary: B2B contract for a Mid/Senior FullStack Engineer to modernize and migrate legacy .NET applications to a modular, cloud-native Azure architecture in the banking sector. The role combines backend development in .NET with frontend work in React, focusing on refactoring legacy systems, building scalable APIs, and implementing CI/CD and observability practices. Hybrid work model with strong influence on architectural decisions and cloud migration. 🗂️ Requirements: 5+ years of commercial experience with C# and .NET (Framework and .NET Core/6+), Strong proficiency in EF Core and MSSQL (query tuning, transactions, indexing), Commercial experience with React and TypeScript, Experience building and securing REST APIs (authentication, versioning, validation), Familiarity with Azure services (App Service, Functions, SQL, Service Bus, Storage), Experience with automated testing (unit, integration, contract, E2E), Experience with CI/CD pipelines (Azure DevOps or GitHub Actions), Ability to work with legacy .NET codebases (ASP.NET MVC, Razor, WPF, WinForms), English at B2+ level 📃 Skills: C#, .NET, .NETCore, .NET6, .NET8, EFCore, MSSQL, T-SQL, React, TypeScript, REST, Azure, AppService, AzureFunctions, AzureSQL, ServiceBus, AzureStorage, xUnit, Jest, Playwright, Cypress, Git, AzureDevOps, GitHubActions, ASP.NET, MVC, Razor, WPF, WinForms, DDD, CleanArchitecture 🏢 Description: We are looking for FullStack Engineer (.NET & React) Location: Kraków / Hybrid (7 days in the office per month) Contract Type: B2B Contract Seniority: Mid / Senior About the Project Join a high-impact modernization initiative for a leading player in the banking sector . We are transforming a portfolio of approximately a dozen .NET applications and MSSQL databases into a modular, cloud-native Azure architecture. As a FullStack Engineer, you will play a dual role: evolving existing production services (including legacy UI and desktop components) while systematically extracting business logic to re-implement it into a modern, scalable ecosystem. This is a unique opportunity to influence the transition from monolithic architectures to high-performance, distributed cloud services. Your Responsibilities Design & Development: Build backend services and APIs using .NET 6/8 following Clean Architecture and DDD patterns. Frontend Evolution: Develop and maintain React + TypeScript frontends, managing the incremental migration from legacy UI modules. Modernization: Read, refactor, and extract complex business logic from legacy .NET codebases and T-SQL stored procedures. Quality Assurance: Write and maintain comprehensive automated tests (Unit, Integration, Contract, and E2E). DevOps & Observability: Create CI/CD pipelines (Azure DevOps/GitHub Actions) and instrument services for deep observability (metrics, logs, distributed traces). Collaboration: Participate in domain modeling, architecture discussions, and Agile ceremonies with Architects and Product Owners. Skills & Experience We Require Experience: 5+ years of commercial experience with C# and the .NET ecosystem (both Framework and .NET Core/6+). Database Expertise: Strong proficiency in EF Core and MSSQL (including query tuning, transactions, and indexing). Frontend: Solid production experience with React and TypeScript. Web Services: Practical experience in building and securing REST APIs (Auth, Versioning, Validation). Cloud: Familiarity with Azure services (App Service, Functions, SQL, Service Bus, Storage). Testing & Tooling: Experience with xUnit, Jest, and Playwright/Cypress, as well as disciplined Git practices. Legacy Handling: The ability to read and reason about legacy codebases (ASP.NET MVC, Razor, WPF, or WinForms). Communication: English at a B2+ level for technical documentation and team collaboration. Nice to Have Experience with Infrastructure as Code (Terraform or Bicep). Knowledge of Docker and Kubernetes (AKS). Background in migrating monoliths to microservices. Azure Developer Associate certification. What We Offer Impact: Real influence on the architecture and the cloud migration roadmap. Autonomy: Direct collaboration with Tech Leads and Architects in a flat structure. Modern Stack: Opportunity to work with the latest .NET versions (6/8) and React. Efficiency: Fast technical onboarding with immediate access to repos, CI/CD pipelines, and monitoring tools. Flexible Hybrid Model: Remote-first approach with only 7 planned days in the Kraków office per month. Benefits : Luxmed and Multisport Card

🏢 Summary: Senior Full Stack Developer role focused on architecting and delivering high-performance web applications using React and Node.js. The position involves leading system design, building scalable front-end and back-end solutions, and overseeing cloud-based deployments and DevOps processes. The role includes technical ownership of microservices, APIs, databases, and application performance in a hybrid Warsaw-based setup. 🗂️ Requirements: 7+ years full stack development experience, 2+ years in senior or technical lead role, Expert-level React.js with Hooks and Redux, Advanced JavaScript ES6+ proficiency, Strong Node.js and Express.js experience, Experience designing REST or GraphQL APIs, Experience with OAuth, JWT, sessions, RBAC, Database design and optimization with PostgreSQL, MySQL, or MongoDB, Hands-on Docker experience, Experience with AWS, Azure, or GCP, CI/CD pipeline management experience, Proficiency with Git workflows, Bachelor’s or Master’s in Computer Science or related field 📃 Skills: React, Redux, JavaScript, HTML5, CSS3, Node.js, Express, GraphQL, REST, OAuth, JWT, RBAC, PostgreSQL, MySQL, MongoDB, Docker, Kubernetes, AWS, Azure, GCP, Git, CI/CD, Webpack, Babel, Vite 🏢 Description: 🧩 About the Company Our client is a rapidly growing US-based technology firm with global operations. With a strong commitment to innovation and quality engineering, the company is building a new engineering hub in Warsaw. This is your opportunity to join a high-performing team and play a pivotal role in developing next-generation digital solutions for the private capital markets. 📍 Location & Setup Start remotely and transition to a hybrid model based in Warsaw (3 days/week in the office in the coming months). 🧠 The Role: Senior Full Stack Developer (React & Node.js) We’re looking for an expert-level Senior Full Stack Developer with at least 7 years of professional experience in designing, architecting, and delivering high-performance web applications. You will take ownership of complex technical challenges across both the front-end and back-end, drive architectural decisions, and provide technical leadership and mentorship within the software development lifecycle. 🔧 Key Responsibilities Technical Leadership: Architect and develop scalable, responsive UIs with React.js, Redux, and modern JavaScript (ES6+). System Design: Design, build, and scale advanced server-side applications, microservices architecture, and RESTful/GraphQL APIs with Node.js and Express. Data Architecture: Lead database design, optimization, and integration strategies (PostgreSQL, MySQL, or MongoDB). Quality Assurance: Define testing strategies, write robust unit/integration tests, and establish efficient debugging protocols for the team. DevOps & Deployment: Oversee and optimize CI/CD pipelines, containerization using Docker, and cloud deployments. Agile Mentorship: Lead agile collaboration with product managers, designers, and engineers, while mentoring mid-level and junior developers. Performance: Proactively monitor system performance, identify bottlenecks, and maintain high-availability production-grade applications. Standards: Establish and maintain comprehensive technical documentation and coding standards. 📌 What We’re Looking For Front-End: Expert-level experience with React.js, Hooks, Redux, and complex component-based architecture. Deep mastery of HTML5, CSS3, and ES6+. Advanced configuration and optimization experience with build tools like Webpack, Babel, or Vite. Back-End: Senior-level proficiency in Node.js & Express.js for enterprise applications. Extensive API design and architecture experience (GraphQL highly preferred, alongside REST). Deep understanding and implementation experience with advanced security and authentication protocols: OAuth, JWT, sessions, and RBAC. Databases & DevOps: Proven experience in scaling and optimizing relational and non-relational databases (PostgreSQL, MySQL, or MongoDB). Solid hands-on experience with Docker; Kubernetes experience is highly advantageous. Demonstrated experience designing and deploying applications on cloud platforms (AWS, Azure, or GCP). Advanced proficiency with Git workflows and driving Agile/Scrum methodologies. 🎓 Qualifications Bachelor’s or Master’s in Computer Science or a related field. 7+ years of hands-on experience in full stack development. 2+ years of experience in a senior or technical lead capacity. Proven track record of architecting, deploying, and maintaining high-traffic production applications. 💡 Soft Skills Strategic, analytical thinker and highly effective problem-solver. Strong technical leadership, team collaboration, and cross-functional communication skills. Self-motivated with excellent time management and the ability to drive projects autonomously. Passion for continuous learning, adopting new technologies, and sharing knowledge with the team. 🎁 What’s Offered Competitive salary up to $6,200 USD/month. Hybrid remote role with 3 days form office in the heart of Warsaw Generous Paid Time Off (PTO). Comprehensive full benefits package. The unique chance to shape the technical foundation of a new engineering hub and lead high-impact projects. A supportive, innovation-driven work environment that values technical excellence.