Senior .NET Engineer

Senior • Remote

22,000 - 26,000 PLN

Warsaw, Poland

Coldrun is a Warsaw-based software engineering company building custom software for real-world operations.

As a partner to an innovative US-based tech company, we are looking for a Senior Back-end Engineer (.NET) to help develop and scale an ERP-class, multi-tenant SaaS platform that automates production, dispatch, and logistics workflows.

You will join a team working on a modular, domain-driven system built with .NET and SQL Server, deployed on Microsoft Azure, and supporting real-time operations across multiple plants, fleets, and business units.

Requirements

6+ years of experience with Microsoft .NET, including at least 4 years with modern .NET (Core / 5+)
3+ years building production-grade, enterprise-level applications
Strong understanding of RESTful API design, SOLID, DDD, OOP, and common design and architectural patterns
Solid experience with Entity Framework Core (or similar ORM), including migrations and query optimization
Deep knowledge of SQL Server, including schema design, indexing, and execution plan analysis
Experience building scalable, multi-tenant or N-tier SaaS systems
Hands-on experience with Microsoft Azure
Experience securing APIs using JWT and OAuth2 / OpenID Connect, including role-based and permission-based access
Familiarity with Docker, Git, CI/CD pipelines, and Agile workflows
Availability to work US East Coast business hours (-6h) at least 2 days per week
Fluent communication in English and Polish

Nice to have

Experience with real-time systems (SignalR or similar)
Exposure to observability tooling (DataDog, Application Insights)
Experience with performance or load testing (JMeter, or similar)
Experience with Azure DevOps
Experience integrating external systems via webhooks or event-driven architectures

What we offer

Remote-first setup or hybrid option (Warsaw)
Flexible working hours
Private healthcare
Sports and leisure package
Long-term, stable cooperation
International working environment
Regular team and company events

Coldrun

Coldrun is a Warsaw-based software engineering company specializing in the development of custom software solutions designed to support real-world operational processes. The company partners with innovative technology firms, including US-based organizations, to build and scale advanced enterprise platforms such as ERP-class, multi-tenant SaaS systems. With expertise in modern Microsoft technologies and cloud infrastructure, Coldrun focuses on delivering modular, domain-driven systems that enable efficient production, dispatch, and logistics operations. The company operates in an international environment and emphasizes long-term collaboration, technical excellence, and practical, scalable solutions tailored to complex business needs.

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