Expert Fullstack .NET & TS developer

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) 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• 25–30 EUR/h + paid days off (B2B) • An alternative higher-rate option is available without paid leave • Remote-first culture with regular in-person collaboration. Presence in our Gdańsk office 2 days per week is expected. • 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!