Senior .Net Engineer

N-iX; Kraków; Hybrid; PLN 180,000 - 240,000; Full time

Benefits offered by this job

Flexible format

Competitive salary

Career growth

Mentorship program

Education reimbursement

Team events

Job summary

N-iX in Kraków is seeking an experienced .NET Engineer to drive a large-scale modernization from .NET Framework 4.8 to .NET 10, spanning the full backend stack and Linux readiness. You will refactor legacy patterns, migrate EF6 to EF Core, collaborate with DevOps on containers and AWS deployment, and help deliver a phased, production-safe migration within an Agile team.

You will work with a cross-functional group, integrating testing, CI/CD, and modern architecture practices to ensure scalable,

Qualifications

• 5+ years of C# and .NET backend development with strong knowledge of ASP.NET and ASP.NET Core.
• Proven, hands‑on experience migrating .NET Framework applications to .NET Core / .NET 8, 10 in production.
• Solid experience with EF Core.Solid knowledge of DDD, CQRS, and repository patterns in layered .NET architectures.
• Familiarity with Docker multi‑stage builds and Linux container fundamentals for .NET applications.Proficient with xUnit and Moq for unit testing; comfortable with container-wired test setups.
• Experience with AWS ECS / Fargate and ECR for deploying containerized .NET applications.
• Familiarity with MassTransit and RabbitMQ or Amazon MQ for event‑driven messaging.
• Experience with Hangfire or similar background job processing frameworks.
• Proficient in Git and familiar with Agile/SCRUM team processes.

Responsibilities

• Migrate a .NET Framework 4.8 application to .NET 10.
• Migrate a large database-first Entity Framework 6 model to EF Core 8 across multiple bounded contexts, one domain at a time.
• Identify and replace Windows-only libraries and assembly references that prevent building and running on Linux.
• Establish unit test coverage measurement and enforce quality gates as part of the migration pipeline.
• Collaborate with the DevOps engineer on Dockerfile authoring, environment configuration, and secrets injection.
• Participate in Agile/SCRUM processes, conduct code reviews, and document migration decisions.

Skills

C#/.NET

ASP.NET Core

Migration to .NET 8/10

DDD/CQRS

Unit testing (xUnit)

Docker

Linux

AWS

EF Core

Git

CI/CD for .NET

Angular SPA familiarity

Code coverage tools

Performance tuning

Tools

MassTransit

RabbitMQ

Docker

AWS ECS/Fargate

EF Core tooling

Job description

As a .NET Engineer you will drive the technical modernization of a large-scale system from .NET Framework 4.8 to .NET 10. Your work will span the full backend stack — replacing Windows-only dependencies, refactoring legacy patterns, migrating data access to EF Core, and ensuring every service is portable, containerizable, and ready for AWS cloud deployment. You will collaborate closely with DevOps and database engineers as part of a cross-functional Agile team delivering a phased, production-safe migration.

Responsibilities

• Migrate a .NET Framework 4.8 application to .NET 10.
• Migrate a large database-first Entity Framework 6 model to EF Core 8 across multiple bounded contexts, one domain at a time.
• Identify and replace Windows-only libraries and assembly references that prevent building and running on Linux.
• Establish unit test coverage measurement and enforce quality gates as part of the migration pipeline.
• Collaborate with the DevOps engineer on Dockerfile authoring, environment configuration, and secrets injection.
• Participate in Agile/SCRUM processes, conduct code reviews, and document migration decisions.

Must-Have Qualifications

• 5+ years of C# and .NET backend development with strong knowledge of ASP.NET and ASP.NET Core.
• Proven, hands‑on experience migrating .NET Framework applications to .NET Core / .NET 8, 10 in production.
• Solid experience with Entity Framework Core.Solid knowledge of DDD, CQRS, and repository patterns in layered .NET architectures.
• Familiarity with Docker multi‑stage builds and Linux container fundamentals for .NET applications.Proficient with xUnit and Moq for unit testing; comfortable with container-wired test setups.
• Experience with AWS ECS / Fargate and ECR for deploying containerized .NET applications.
• Familiarity with MassTransit and RabbitMQ or Amazon MQ for event‑driven messaging.
• Experience with Hangfire or similar background job processing frameworks.
• Proficient in Git and familiar with Agile/SCRUM team processes.

Nice-to-Have Skills

• Experience building CI/CD pipelines for .NET projects.
• Familiarity with micro‑frontend architecture and Angular‑based single‑page applications.
• Experience with automated code coverage tooling and enforcing coverage thresholds in CI.
• Experience with performance optimization and scalable enterprise backend systems.

We offer

• Flexible working format - remote, office-based or flexible
• A competitive salary and good compensation package
• Personalized career growth
• Professional development tools (mentorship program, tech talks and trainings, centers of excellence, and more)
• Active tech communities with regular knowledge sharing
• Education reimbursement
• Memorable anniversary presents
• Corporate events and team building
• Other location‑specific benefits
• not applicable for freelancers