Fullstack Developer – .NET and React.js

Are you a skilled .NET Developer with a knack for front-end work in React, eager to take on new challenges in a global environment?Would you enjoy combining hands-on coding with occasional travel to the U.S., including a 2-week onboarding in beautiful North Carolina? If so, this opportunity might be just what you’re looking for!

Sii is collaborating with a U.S.-based technology company specializing in enterprise monitoring and observability solutions. Known for their modern approach and highly scalable products, their tools are used by major organizations worldwide to ensure reliability, performance, and real-time insights across complex systems.

In this role, you’ll join a dynamic, cross-functional team and contribute to impactful products with global reach. If you're excited about .NET, React, and the chance to work internationally—apply now!

Your responsibilities

• Leading the design and development of complex, scalable web solutions using OOP principles and technologies such as React (TypeScript) and .NET (C#)

• Ensuring engineering excellence by writing clean, testable code and ensuring thorough unit testing

• Applying test-first approaches like test-driven development (TDD) and behaviour-driven development (BDD) beyond unit tests

• Collaborating closely with product managers to define software functionality

• Working with architects and UX designers to implement system architecture and designs

• Engaging with other stakeholders to align on software requirements and solutions

Our requirements

• At least 7 years of experience in software development, with at least 4 years focusing on a commercial software product

• Expert-level knowledge of React (TypeScript), and .NET (C#), with a strong understanding of OOP principles and design patterns

• Proficiency with relational databases (e.g., PostgreSQL, Oracle) and ORM frameworks (.NET Entity Framework)

• Experience setting up CI/CD pipelines (GitLab CI/CD) and utilizing DevOps practices

• Knowledge of microservices architecture and containerization, e.g., Docker, Kubernetes

• Familiarity with cloud platforms, e.g., AWS

• Previous work with cross-functional teams and various stakeholders

This is how we work on a project

• Continuous Deployment

• Continuous Integration

What we offer

• Great Place to Work since 2015 - it’s thanks to feedback from our workers that we get this special title and constantly implement new ideas

• Employment stability - revenue of PLN 2.1BN, no debts, since 2006 on the market

• We share the profit with Workers - over PLN 60M has already been allocated for this aim since 2022

• Attractive benefits package - private healthcare, benefits cafeteria platform, car discounts and more

• Comfortable workplace – class A offices or remote work

• Dozens of fascinating projects for prestigious brands from all over the world – you can change them thanks to Job Changer application

• PLN 1 000 000 per year for your ideas - with this amount, we support the passions and voluntary actions of our workers

• Investment in your growth – meetups, webinars, training platform and technology blog – you choose

• Fantastic atmosphere created by all Sii Power People

Recruitment stages

1 Send your CV

2 Talk to us about your expectations

3 Learn more about our projects and choose the best

4 Start your adventure with Sii!

Sii Sp. z o.o.

Sii is the leading technology consulting, digital transformation, engineering, and business services vendor in Poland. We already employ more than 7 500 professionals and implement projects in a variety of industries for clients from many countries around the world.

The Great Place to Work title, won 10 times in a row, proves that at Sii we create a friendly work environment. In a survey, as many as 90% of our employees responded that Sii is a great place to work, and 95% of them think we have a great atmosphere here.