10/22/2026 updated
80 % partially available
Senior .NET / C# Backend Engineer | Microservices, Event-Driven, Azure | 8+ years
Katowice, Poland
Only remote
MSc Computer Science, University of Economics in KatowiceAbout me
Senior .NET backend engineer based in Katowice, Poland (CET). I turn ad-hoc code into maintainable services, design event-driven systems and take ownership from the first commit to production support. Remote, B2B, part-time.
Azure DevOpsASP.NET.NET FrameworkMicrosoft AzureC Sharp (Programming Language)Entity FrameworkPostgreSQLMicrosoft SQL ServersRabbitMQAzure Service Bus.NET CoreEvent-driven ArchitectureBackendKubernetesApache Kafka
Senior .NET / C# backend engineer with 8+ years of commercial experience building and maintaining backend systems, APIs and integrations for healthcare, banking and cyber-risk platforms. Available for remote, part-time B2B contracts (up to 30 hours per week).
Backend: C#, .NET 10 / 8 / 7, .NET Framework, ASP.NET Core, Web API / REST, Entity Framework Core, MediatR, Blazor
Messaging and event-driven architecture: RabbitMQ, Azure Service Bus, Apache Kafka, WolverineFX, MassTransit, NServiceBus
Architecture: microservices, event-driven systems, legacy modernization, integration testing
Databases: MS SQL Server, PostgreSQL, Cosmos DB
Cloud and DevOps: Microsoft Azure, Azure DevOps, Docker, Kubernetes, IIS, Jenkins, Octopus Deploy, CI/CD
Frontend (supporting): Angular, Vue.js, TypeScript
Selected experience:
– Re-architected an ad-hoc backend into microservices and designed the entire event-driven architecture of a cyber-risk quantification platform; replaced MassTransit with WolverineFX and built the integration-testing framework.
– Built an intra-group settlement platform for ING from scratch (.NET, Kafka); acted as Scrum Master and team lead for 7 developers, working with business stakeholders across EMEA.
– Maintain and develop a production medical appointment system; resolved production issues in RabbitMQ queues and built internal developer tooling.
– Built backend services for an I-9 document workflow platform for B2B customers in the USA and Canada; acting team lead for 3 developers.
Ways of working: Scrum, code reviews, mentoring, technical documentation, AI-assisted development. Languages: Polish (native), English (C1).
Experience
Professional experience5 - 10 years
Freelancer since2022
Languages
EnglishFluentPolishNative speaker
Project history
Healthcare: medical appointment system.
– Maintain and develop the production system that handles medical appointments, from incident analysis to new features.
– Diagnosed and resolved several production issues in RabbitMQ message queues.
– Built and proposed two internal developer tools: a local environment manager and a dependency-graph generator that maps links between projects and repositories.
Stack: C#, .NET 8+, .NET Framework, RabbitMQ, MassTransit, MS SQL Server, Docker, IIS, Jenkins
Cyber risk quantification platform for corporate clients (startup, PL/DE team of ~10).
– Re-architected an ad-hoc backend into microservices.
– Designed and built the platform's entire event-driven architecture.
– Introduced WolverineFX, replacing the existing MassTransit setup.
– Created the integration-testing framework for the platform's services.
– Authored most of the team's architecture proposals, with final calls made together with the tech lead.
Stack: C#, ASP.NET Core, .NET 10 / 8, EF Core, WolverineFX, MassTransit, Azure Service Bus, PostgreSQL, Cosmos DB, Azure DevOps
Banking: intra-group settlement platform used by ING entities in many countries.
– Built the settlement platform from scratch with the team: backend services, REST APIs, and Kafka for messaging between services and log publishing.
– Six months in, took over the Scrum Master role and business-facing work alongside the Product Owner, becoming the lead of a 7-developer team.
– Planned the work, owned delivery and reporting, agreed scope with business stakeholders across EMEA, and wrote technical and business documentation.
– Improved the team's efficiency by organizing the workflow, onboarding new developers, mentoring and reviewing code.
Stack: C#, ASP.NET Core 7, EF Core, MediatR, Kafka, MS SQL, Angular 14, Docker, Kubernetes, Azure DevOps