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!