Senior Fullstack Developer - .NET/React

🏢 Summary: Full-Stack Developer role focused on building and enhancing business applications using C#/.NET on the backend and React (18+) on the frontend. The position involves developing new features, maintaining and improving legacy code, and contributing to solution design within an Agile/Scrum team. Strong emphasis on backend expertise, frontend development, and architectural best practices. 🗂️ Requirements: 5+ years of experience with .NET and C#, 3+ years of experience with React (18+), Strong knowledge of .NET Framework, .NET Standard, .NET Core/.NET, Experience with debugging, profiling and performance analysis, Understanding of DDD, Clean Code and SOLID principles, Knowledge of architectural patterns and asynchronous communication, Good command of T-SQL, Experience with SQL Server Management Studio (SSMS), Experience with Visual Studio 📃 Skills: C#, .NET, React, TSQL, SQLServer, SSMS, VisualStudio, DDD, SOLID, CleanCode, Scrum, Debugging, Profiling, Architecture, Asynchronous 🏢 Description: We’re looking for an experienced Full-Stack Developer to build and evolve business applications using C#/.NET on the backend and React on the frontend. You’ll work closely with a cross-functional team (QA, Analysts, Product Owner) in an Agile/Scrum environment, contributing to both new development and improvements to existing (including legacy) codebases. Key responsibilities: Develop software in C# based on functional and technical documentation Build and maintain the frontend using React (18+) Analyse and improve existing code, including legacy components Contribute to solution design and architecture Collaborate daily with developers, testers, analysts and the Product Owner in Scrum Requirements: 5+ years of experience building applications with .NET / C# 3+ years of experience building applications with React Strong knowledge of C# (.NET Framework, .NET Standard, .NET Core/.NET) React experience with modern versions (React 18+) Practical skills in debugging, profiling and performance analysis Understanding of DDD, Clean Code, SOLID Knowledge of architectural patterns and asynchronous communication Good command of T-SQL and SQL Server Management Studio (SSMS) Experience working with Visual Studio Nice to have Experience building views/UI for mobile applications Background in projects for the financial sector Test automation experience (e.g., Postman, Playwright) Familiarity with WCAG accessibility standards

🏢 Summary: Fullstack Developer role focused on building and enhancing dynamic web applications using .NET on the backend and React on the frontend. The position involves developing robust, high-performance solutions, integrating APIs, and resolving complex technical issues within a collaborative team environment. Strong emphasis is placed on delivering seamless end-to-end functionality. 🗂️ Requirements: 5+ years of fullstack development experience, .NET backend expertise, Strong React knowledge, Experience with WCF and REST APIs, Database management experience, Proficiency in HTML, JavaScript, CSS, Understanding of message queues, Fluent English communication 📃 Skills: .NET, C#, React, REST, WCF, SQL, HTML, JavaScript, CSS, Databases, MessageQueues, English 🏢 Description: Summary: The ideal candidate is expected to function as a Fullstack Developer, contributing both front-end and back-end functionalities with a strong focus on .NET and React technologies. The primary goal is to enhance the team's capabilities in developing seamless, robust applications. Main Responsibilities: Engage in full-stack development to create dynamic web applications. Implement the front-end components using React. Develop back-end services using .NET. Communicate effectively with team members and stakeholders in English. Investigate and resolve complex technical problems proactively. Collaborate with team members to enhance application performance and usability. Key Requirements: 5+ years of experience in fullstack development. Expertise in .NET for backend development. Strong understanding of React for frontend development. Fluent communication skills in English. Knowledge of Web APIs (WCF and REST APIs). Familiarity with database management. Competence in HTML, JavaScript, and CSS. Understanding of message queues. Nice to Have: Experience with cloud services or platforms. Familiarity with CI/CD practices. Exposure to Agile methodologies.

🏢 Summary: Fullstack Developer role focused on building and enhancing dynamic web applications using .NET on the backend and React on the frontend. The position involves developing robust services, implementing responsive UI components, and resolving complex technical issues. The goal is to strengthen the team’s capability to deliver high-performance, scalable applications. 🗂️ Requirements: 5+ years of fullstack development experience, .NET expertise for backend development, Strong React knowledge for frontend development, Experience with Web APIs (WCF, REST), Database management experience, Proficiency in HTML, JavaScript, CSS, Understanding of message queues 📃 Skills: .NET, React, WCF, REST, WebAPI, HTML, JavaScript, CSS, SQL, Databases, MessageQueues 🏢 Description: Summary: The ideal candidate is expected to function as a Fullstack Developer, contributing both front-end and back-end functionalities with a strong focus on .NET and React technologies. The primary goal is to enhance the team's capabilities in developing seamless, robust applications. Main Responsibilities: Engage in full-stack development to create dynamic web applications. Implement the front-end components using React. Develop back-end services using .NET. Communicate effectively with team members and stakeholders in English. Investigate and resolve complex technical problems proactively. Collaborate with team members to enhance application performance and usability. Key Requirements: 5+ years of experience in fullstack development. Expertise in .NET for backend development. Strong understanding of React for frontend development. Fluent communication skills in English. Knowledge of Web APIs (WCF and REST APIs). Familiarity with database management. Competence in HTML, JavaScript, and CSS. Understanding of message queues. Nice to Have: Experience with cloud services or platforms. Familiarity with CI/CD practices. Exposure to Agile methodologies.

🏢 Summary: Hybrid Fullstack Engineer role in Warsaw focused on building scalable enterprise applications using Node.js, C#, .NET, React, AngularJS, and SQL Server. The position involves backend and frontend development, architecture contributions, and collaboration with cross-functional engineering teams. Experience with cloud-native and containerized technologies is considered a plus. 🗂️ Requirements: 7+ years of full-stack development experience, Expertise in React, Expertise in Node.js, Expertise in C#, Expertise in ASP.NET, Strong SQL Server experience, Experience building scalable enterprise applications, Experience developing APIs, Strong application design skills, Analytical and problem-solving skills, Attention to software quality, Communication skills, Collaboration skills 📃 Skills: Node.js, C#, .NET, React, AngularJS, SQL, T-SQL, ASP.NET, SQLServer, APIs, Cloud, Containers, Streaming 🏢 Description: Fullstack Engineer Warsaw, hybrid. Responsibilities Develop and maintain server-side applications using Node.js, C#, and .NET . Build responsive user interfaces with React and AngularJS . Design and optimize SQL Server solutions, including T-SQL and stored procedures. Contribute to application architecture, technical design, and technology decisions. Build scalable solutions leveraging modern cloud, container, and streaming technologies. Collaborate with cross-functional engineering teams to deliver high-quality software. Requirements 7+ years of full-stack development experience . Strong hands-on expertise in React, Node.js, C#, ASP.NET , and SQL Server . Experience developing scalable enterprise applications and APIs. Strong application design, analytical, and problem-solving skills. High attention to detail and commitment to software quality. Excellent communication and collaboration skills. Nice to Have Experience with cloud-native, containerized, or event-driven architectures. Financial services or large enterprise environment experience.

🏢 Summary: Fullstack Developer role focused on building scalable web applications using ASP.NET, C#, and React, with strong emphasis on API design, event-driven architecture, and cloud-native environments. The position involves end-to-end development, CI/CD practices, containerized deployments, and collaboration in agile teams. Ideal for engineers experienced in backend services, modern frontend ecosystems, and orchestration tools. 🗂️ Requirements: Strong experience with ASP.NET, Strong experience with C#, Experience building scalable backend services and APIs, Strong experience with React, Understanding of modern frontend architecture, Experience with API design, Experience with GitLab CI/CD, Experience with RabbitMQ, Experience with Docker, Experience with Kubernetes 📃 Skills: ASP.NET, C#, React, TanStack, Tailwind, Playwright, RabbitMQ, Docker, Kubernetes, GitLab, Linux, Unity, APIs, CI/CD 🏢 Description: Role Overview We are looking for a skilled Fullstack Developer with strong backend expertise in ASP.NET and C#, combined with modern frontend development using React. The role involves building scalable web applications, designing robust APIs, and contributing to cloud-native and event-driven architectures. The ideal candidate is comfortable working across the full stack, collaborates well in agile teams, and has an interest in modern tooling, orchestration, and frontend ecosystems. Core Responsibilities • Design, develop, and maintain scalable fullstack applications • Build and maintain backend services using ASP.NET and C# • Develop responsive and modern frontend applications using React • Design and integrate APIs and asynchronous communication flows • Collaborate with developers, designers, QA, and DevOps teams • Contribute to architecture discussions and technical decisions • Ensure code quality through testing, reviews, and CI/CD practices • Participate in deployment, monitoring, and troubleshooting activities Must-Have Skills Backend • Strong experience with ASP.NET • Strong experience with C# • Experience building scalable backend services and APIs Frontend • Strong experience with React • Good understanding of modern frontend architecture and component-based development Should-Have Skills • Experience with GitLab Pipelines / CI-CD • Experience with API design and best practices Frontend Libraries & Tooling • Experience with: o TanStack o Tailwind CSS o Playwright o AI agent development (Kiro, Claude, Cursor) Messaging & Async Communication • Experience with: o RabbitMQ o Event-driven and asynchronous communication patterns • Understanding of async workflows across frontend and backend systems Infrastructure & Orchestration • Experience with: o Docker o Kubernetes • Familiarity with containerized deployments and orchestration Nice-to-Have Skills • Interest or experience in Unity / game development • Strong Linux competence Preferred Qualifications • Experience working in agile development environments • Strong problem-solving and debugging skills • Understanding of scalable and maintainable software architecture • Good communication and collaboration skills • Passion for learning modern technologies and frameworks Tech Stack Summary Area Backend: ASP.NET, C# Frontend: React Frontend Libraries: TanStack, Tailwind, Playwright Messaging: RabbitMQ Infrastructure: Docker, Kubernetes CI/CD: GitLab Pipelines Additional: Linux, API Design, Unity

🏢 Summary: Senior Full-Stack Developer role focused on enhancing a platform using React and TypeScript on the frontend and .NET/C# with SQL Server on the backend. The position emphasizes strong frontend expertise while maintaining sufficient backend knowledge for independent task execution. Experience with legacy systems is considered an advantage. 🗂️ Requirements: 5+ years full-stack development experience (Mid) or 10+ years (Senior), Proficiency in React, Proficiency in TypeScript, Strong knowledge of modern JavaScript, Solid knowledge of C# and .NET, Ability to work with SQL Server 📃 Skills: React, TypeScript, JavaScript, C#, .NET, SQL, SQLServer, ClassicASP 🏢 Description: Summary: A senior full-stack developer position focused on enhancing our platform through modern technologies, primarily using React and TypeScript on the frontend and .NET/C# with SQL Server on the backend. Main Responsibilities: Strengthen the focus on React and TypeScript as the primary and most critical skills, with a solid foundation in modern JavaScript. Utilize .NET/C# and SQL Server as supporting skills to ensure self-sufficiency in day-to-day tasks without primary responsibility for complex backend or database optimization. Leverage knowledge of legacy technologies, such as Classic ASP, for understanding existing logic as a nice-to-have skill. Key Requirements: At least 5 years of experience (Mid-level) or 10 years (Senior-level) in full-stack development. Proficiency in React and TypeScript. Solid foundation in modern JavaScript and C# / .NET. Nice to Have: Experience with legacy systems like Classic ASP.

🏢 Summary: Senior Full Stack Developer role focused on building and maintaining scalable financial-sector applications using .NET and React. The position involves backend and frontend development, API design, automated testing, and collaboration with cross-functional teams in a global engineering environment. 🗂️ Requirements: 6+ years of Full Stack Development experience, Strong knowledge of C#, Strong knowledge of .NET, Strong knowledge of React, Experience with Microsoft SQL Server, Experience with REST APIs, Experience with automated testing, Experience with CI/CD, Experience with Git, Experience with Docker, Understanding of software architecture, Understanding of microservices, Understanding of distributed systems, Strong problem-solving skills, Strong communication skills, Fluent English 📃 Skills: C#, NET, React, SQL, REST, Git, Docker, CI/CD, Microservices 🏢 Description: Senior Full Stack Developer (.NET & React) We are looking for an experienced Senior Full Stack Developer to join a global engineering team building business-critical applications for the financial sector. You will be responsible for designing, developing, and maintaining scalable backend services and modern web applications, working closely with business stakeholders and cross-functional teams. Responsibilities Design, develop, and maintain applications using C#/.NET and React . Build scalable APIs and responsive user interfaces. Collaborate with business and technical teams to deliver high-quality solutions. Write automated tests and contribute to CI/CD and DevOps best practices. Support production systems and drive continuous improvements in performance and reliability. Requirements 6+ years of experience as a Full Stack Developer. Strong expertise in C#/.NET , React , and Microsoft SQL Server . Experience with REST APIs, automated testing, CI/CD, Git, and Docker. Good understanding of software architecture, microservices, and distributed systems. Strong problem-solving and communication skills. Fluent English. Nice to Have Experience in the financial services or trading domain. Experience working in distributed, international teams.

🏢 Summary: Senior Full Stack Developer role focused on building high-performance, data-driven web applications with a strong emphasis on React and complex graph visualizations. The position involves developing scalable Node.js APIs and transforming large-scale graph data into interactive UI components. Fully remote B2B contract within a Poland-based team working standard business hours. 🗂️ Requirements: 7+ years of software development experience, Expert knowledge of React and TypeScript, Strong experience with Node.js and TypeScript for server-side development, Experience building REST and GraphQL APIs, Extensive experience with Redux state management, Proficiency with Storybook for component-driven development, Ability to optimize frontend performance for large-scale datasets, High proficiency in English (B2/C1) 📃 Skills: React, TypeScript, Node.js, Redux, GraphQL, REST, D3.js, GoJS, Cytoscape, Neo4j, Cypher, AGGrid, Storybook, Microservices 🏢 Description: Senior Full Stack Developer (React / Node.js ) The Role As a Full Stack Developer with a strong emphasis on React , you will be responsible for crafting the visual and interactive elements of applications that visualize complex financial and ownership networks. While the backend is built on Node.js , your primary challenge will be turning intricate graph data into seamless, high-performance UI components. Key Responsibilities React Excellence: Lead the development of complex, data-driven web applications using React and TypeScript . Graph Visualization: Transform raw graph data into interactive, responsive UIs using D3.js, GoJS , or similar libraries. Backend Services: Develop and maintain scalable APIs and microservices using Node.js and TypeScript . Data Integration: Work closely with graph engineers to integrate real-time GraphQL data and high-end AG Grid reports. Performance: Optimize the frontend to handle and render large-scale, nested datasets without lag. Architecture: Maintain reusable components in Storybook and ensure a consistent, scalable codebase. Technical Requirements (Must Have) 7+ years of experience in software development. Expert React & TypeScript: Deep knowledge of modern React patterns and performance tuning. Node.js & TypeScript: Solid experience in building server-side applications and REST/GraphQL APIs. State Management: Extensive experience with Redux . Modern Tooling: Proficiency with Storybook for component-driven development. English: High proficiency ( B2/C1 ) for daily collaboration with US and Netherlands-based stakeholders. Nice to Have Data Viz: Experience with D3.js, GoJS , or Cytoscape . Graph Databases: Familiarity with Neo4j, or Cypher Reporting: Advanced knowledge of AG Grid . Assignment Details Contract Type: B2B Work Model: 100% Remote / Work from Home Business Hours: 9:00 – 17:00 (Warsaw Time) Location: Poland-based delivery team

🏢 Summary: Full-Stack Front-End Developer role focused on building and enhancing modern, cloud-based web applications with strong emphasis on user experience, performance, and scalability. The position involves developing frontend features in React.js, integrating with Java backend services, and working within AWS environments. The role includes maintaining existing applications, optimizing performance, and contributing to best development practices in an Agile team. 🗂️ Requirements: Minimum 3 years commercial experience with React.js, Minimum 3 years commercial experience with JavaScript, Minimum 3 years commercial experience with TypeScript, Minimum 3 years commercial experience with Java, Minimum 3 years commercial experience with AWS, Experience building responsive web applications, Experience integrating frontend applications with APIs, Understanding of frontend architecture, Knowledge of Agile methodologies 📃 Skills: React.js, JavaScript, TypeScript, Java, AWS, API, Agile 🏢 Description: We are looking for a Full-Stack Front-End Developer who is passionate about building modern, cloud-based applications and delivering excellent user experiences. You will work on developing and maintaining several existing applications and services, focusing on improving usability, performance, and scalability in a cloud environment. Responsibilities Maintain and develop high-quality user experiences across multiple web applications and services. Build and enhance frontend features using React.js and modern JavaScript frameworks. Collaborate with backend services developed in Java . Improve application performance, usability, and responsiveness. Work with cloud-based environments hosted on AWS . Fix bugs, optimize existing solutions, and introduce improvements. Collaborate closely with developers, product teams, and stakeholders. Contribute to code reviews and follow best development practices. Required Skills Minimum 3 years of commercial experience with: React.js JavaScript TypeScript Java AWS Experience building responsive and user-focused web applications. Understanding of frontend architecture and modern UI development practices. Experience integrating frontend applications with APIs. Knowledge of Agile development methodologies. Strong problem-solving and communication skills.

🏢 Summary: Senior Full Stack Developer role focused on designing, building, and enhancing enterprise-level applications using .NET and React. The position involves contributing to architecture decisions, improving performance and usability, and ensuring application reliability across the full technology stack. It includes ownership of backend services, frontend development, CI/CD processes, and production support. 🗂️ Requirements: Minimum 5 years of professional experience in .NET application development, Strong proficiency in C# and Web API, Hands-on experience with React for web application development, Advanced knowledge of SQL Server and database architecture, Experience with CI/CD pipelines, Understanding of Software Development Life Cycle, Proficiency in HTML5 and CSS, Experience in system architecture and design patterns, Ability to troubleshoot production issues 📃 Skills: .NET, C#, WebAPI, React, SQL, SQLServer, CI/CD, HTML5, CSS, SDLC 🏢 Description: We Are Hiring: Senior Full Stack Developer (.NET and React) We are seeking an experienced Full Stack Developer who is ready to play a key role in designing, building, and improving enterprise-level applications. This position is ideal for someone who enjoys working across the entire technology stack, contributing to architectural decisions, enhancing user experiences, and ensuring application reliability and performance. This is a senior-level opportunity for a professional who combines deep technical expertise with strong analytical thinking and a proactive mindset. Key Responsibilities Contribute to system architecture planning and technical design discussions Drive user interface enhancements to improve usability, performance, and overall application resilience Apply industry-recognized design principles and architectural patterns when implementing solutions Review and interpret business and technical requirements, proposing improvements where appropriate Produce clear and detailed technical documentation for developed features and systems Build proof-of-concept solutions and prototypes to validate architectural approaches Oversee and manage system modifications within structured service management processes Support and enhance automation initiatives across development and operational workflows Deliver high-quality technical support, ensuring timely resolution of issues Collaborate closely with stakeholders to understand objectives and provide effective solutions Required Qualifications and Experience A minimum of Five years of professional experience developing and maintaining production-grade applications within the .NET ecosystem Strong proficiency in C# and Web API development, with experience building secure, scalable, and high-performing backend services Solid hands-on experience with React, developing dynamic, responsive, and performance-optimized web applications Advanced knowledge of database architecture and SQL Server, including complex query development, performance optimization, and tuning Practical experience with continuous integration and continuous delivery pipelines Comprehensive understanding of the Software Development Life Cycle, from requirements analysis through deployment and ongoing support Strong command of modern web standards including HTML5 and Cascading Style Sheets, with the ability to create intuitive user interfaces Excellent analytical and troubleshooting abilities, particularly in demanding production environments High attention to detail and commitment to delivering robust, maintainable solutions If you are passionate about developing high-quality software, improving system performance, and contributing to meaningful technical decisions, we would welcome the opportunity to connect with you. Please feel free to reach out directly or share this opportunity within your professional network. #Hiring #FullStackDeveloper #DotNet #React #SoftwareEngineering #TechnologyCareers