10/24/2026 updated
Premium member
100 % availableSenior .NET Backend Developer | Kafka, IBM MQ & SQL Server | Banking & Fintech | 12 Years
Poznań, Poland
Worldwide
MSc in Computer ScienceOAuth 2.0AI AgentsClean ArchitectureRESTful API Modeling LanguageKubernetes SecuritySql Data WarehouseASP.NET.NET FrameworkAdvanced Message Queuing ProtocolApplication Integration ArchitectureASP.NET MVC FrameworkC Sharp (Programming Language)Command-Query Responsibility Segregation (Software Development)Data ArchitectureData Validation
I'm a Senior .NET backend developer with 12 years of experience building backend solutions in C# with MS SQL, focused on banking, insurance and fintech. I design and develop services in .NET 8 with ASP.NET Core Web API and Entity Framework Core and integrate systems in complex landscapes through Kafka, IBM MQ and REST.
I cover the full cycle: analyzing business requirements, designing backend solutions, building automated unit, integration and end-to-end tests, and keeping solutions stable and performant. I work with Docker and Kubernetes, CI/CD in Jenkins, TeamCity and Azure DevOps, code quality checks in SonarQube, and data processing with SSIS, Redis and KeyDB. My daily tools include Visual Studio, Git, Postman, Insomnia, Jira, Confluence and Bitbucket.
I work directly with business clients and external vendors, agree interface specifications and coordinate integration testing. I'm independent, goal-oriented and consistent in delivering on my commitments, and I pick up new domains and technologies quickly.
Experience
Professional experience10+ years
Freelancer since2025
Languages
EnglishFluentPolishNative speaker
Project history
Payment and transaction integration platform for a retail bank
- Analyzed business requirements with the bank’s business owners and designed backend services in .NET 8 with ASP.NET Core Web API, Entity Framework Core and MS SQL
- Built event-driven integration between core banking, card processing and anti-fraud systems with Kafka and IBM MQ
- Implemented caching and idempotent transaction processing with KeyDB
- Agreed interface specifications and ran integration testing with external vendors
- Unit, integration and end-to-end tests as quality gates in Jenkins, code quality checks with SonarQube
- Deployments to Kubernetes with Docker and Helm, source code in Bitbucket
- Maintenance, performance optimization and production support in a complex system landscape
Team: 6 backend developers, 2 QA, business analyst
Tech: C#, .NET 8, ASP.NET Core Web API, Entity Framework Core, MS SQL, Kafka, IBM MQ, KeyDB, Docker, Kubernetes, Helm, Jenkins, Bitbucket, SonarQube
Metering and billing data platform for an energy utility
- Ingestion of smart meter readings via Kafka, validation and aggregation services in .NET 6
- ETL processes with SSIS into the billing data warehouse on MS SQL
- REST APIs for billing and customer portals with Redis caching
- Containerized services on Kubernetes, CI/CD with Azure DevOps
Tech: C#, .NET 6, ASP.NET Core Web API, Kafka, MS SQL, SSIS, Redis, Docker, Kubernetes, Azure DevOps
Claims processing system for an insurance company
- Backend services for claim registration, assessment workflow and payouts
- Migration of historical claims data from a legacy system with SSIS packages
- Integration with document management and payment systems via REST and message queues
- CI/CD with TeamCity, automated unit and integration tests
Team: 5 developers, QA, Product Owner
Tech: C#, .NET 7, ASP.NET Core Web API, Entity Framework Core, MS SQL, SSIS, Docker, TeamCity, xUnit
Certificates
Apache Kafka (CCDAK)
Confluent2024
Certified Kubernetes Application Developer (CKAD)
The Linux Foundation2023
ISTQB Certified Tester Foundation Level
ISTQB2019
MCP: Programming in C# (70-483)
Microsoft2016