10/19/2026 updated

PR
100 % available

.NET Technical Lead | Senior Backend Software Engineer

Gdansk, Poland
Only remote
MSc in Computer Science, Gdansk University of Technology (2008-2013)
Gdansk, Poland
Only remote
MSc in Computer Science, Gdansk University of Technology (2008-2013)

Profile attachments

cv-piotr-rutkowski-2609.pdf

ASP.NET.NET FrameworkApplication Programming Interfaces (APIs)C Sharp (Programming Language)DevOpsDotNetNukeEntity FrameworkPostgreSQLManaged Extensibility Framework (.NET Framework)Microsoft Networking.NET Framework 4Software ArchitectureRabbitMQRedisSwaggerSQL DatabasesSystems IntegrationTechnical ManagementVirtual Network ComputingAzure Service BusTelerikTest-Driven Development (TDD).NET CoreEvent-driven ArchitectureBackendEvent Driven ArchitectureBackend ProgrammingFull Stack DevelopmentApi DesignASP.NET ApplicationsDomain Driven DesignWeb ApiMicroservices
.NET Backend Development
Expertise in C#, .NET, ASP.NET Core, Entity Framework, REST APIs, OpenAPI/Swagger, OAuth 2.0, and JWT for designing, building, and optimizing backend software solutions and web APIs.

Distributed Systems & Microservices Architecture
Deep knowledge of microservices, Domain-Driven Design (DDD), CQRS, Event Sourcing, Event-Driven Architecture, MassTransit, RabbitMQ, Kafka, Azure Service Bus, AWS SQS, and Temporal for building scalable distributed systems.

Cloud, Containers & DevOps
Hands-on experience with Docker, Kubernetes, Helm, AWS (EC2, S3, RDS, IAM, SQS), Azure (Azure SQL Database, Azure Service Bus, Application Insights), OpenTelemetry, and CI/CD pipelines.

Data & Persistence
Proficiency with PostgreSQL, SQL Server, T-SQL, CockroachDB, MySQL, Redis, and DynamoDB for data storage and access layer design in enterprise applications.

Testing & Quality Assurance
Strong background in automated testing, Playwright, NUnit, Test Strategy, and Test-Driven Development (TDD), including building test suites from scratch and improving test coverage.

Client Application Development
Experience with TypeScript, React, WPF, XAML, and MVVM for building desktop and web client applications, including performance-sensitive UI components.

Technical Leadership
Track record of serving as technical lead, owning architecture and delivery decisions, reviewing code, coaching engineers, and translating business requirements into distributed system capabilities.

Messaging & Integration
Extensive use of RabbitMQ, Kafka, MassTransit, Azure Service Bus, MSMQ, NServiceBus, IBM WebSphere MQ, and WCF for inter-process communication and message-based integrations.

Observability & Performance
Experience with Application Insights, Kusto workbooks, OpenTelemetry, dotMemory, and dotTrace for production observability, memory leak investigation, and performance optimization.

Experience

Professional experience10+ years
Freelancer since2018

Languages

EnglishFluentPolishNative speakerSpanishGood

Project history

Senior Software Developer

Microsoft
Senior software developer contributing to an internal telemetry collection solution. Developed .NET backend functionality supporting telemetry collection and processing. Modernized the platform's serialization layer by replacing the Microsoft Bond serialization library with Protocol Buffers (Protobuf). Technologies: .NET, Protocol Buffers (Protobuf), Microsoft Bond.

Senior Software Engineer

Santander
Senior software engineer contributing to the backend of a swaps trading solution. Delivered .NET backend functionality for a swaps trading platform, implementing planned work items in collaboration with product and engineering stakeholders. Built and maintained data access functionality using DynamoDB. Technologies: .NET, DynamoDB, Microsoft Entra ID.

Senior Software Engineer, Technical Lead

ABSA
Technical lead for the .NET backend of FleetManager, a microservice-based automation platform for corporate server fleets. Accountable for the architecture, technical direction, and end-to-end delivery of the platform's .NET microservices. Owned the architecture and delivery of the platform's .NET microservices and supporting tooling, building the core system from scratch. Made technology, architecture, testing, and delivery decisions for the .NET domain. Technologies: .NET 6-8, MassTransit, RabbitMQ, Entity Framework, CockroachDB, Kubernetes, Temporal, Azure, microservices, Event Sourcing, CQRS.

Senior Software Engineer

Draftable / Affinda
Senior software engineer for Draftable, an enterprise PDF comparison platform serving paid customers and a public web tool. Ported backend components from .NET Framework to .NET Core on Linux. Redesigned backend service orchestration and maintained systems handling thousands of PDF comparisons daily. Refactored the C# codebase for reuse, configuration, and testability. Introduced automated testing, increasing the test suite from zero to approximately 600 tests. Acted as technical lead for the .NET codebase through code reviews and coaching. Technologies: .NET Core, WPF, RabbitMQ, Python, Django, Redis, TypeScript, AWS, TeamCity, SaltStack.

Senior Software Engineer

FlexTrade
Senior software engineer on Spark, a broker-neutral, multi-asset execution management system distributed through Thomson Reuters Eikon and as a standalone application. Developed performance-sensitive WPF desktop functionality. Built SOAP and REST APIs and integrated backend components with internal and third-party systems. Maintained and extended CI/CD workflows using Jenkins and PowerShell. Technologies: C#, WPF, XAML, MVVM Light, .NET Web API, Castle Windsor, Rx.NET, WCF, PostgreSQL, Jenkins.

Senior Software Engineer

JMB Lab
Senior software engineer for SimpleCare.pl, a clinic management system; also served as Scrum Master for a drone detection project. Developed, tested, and maintained desktop and backend functionality for the clinic-management system. Introduced a layered architecture and improved automated test coverage. Facilitated Scrum ceremonies and improved team communication and delivery practices. Technologies: C#, WPF, XAML, Hangfire, .NET Web API 2, PostgreSQL, Ninject, NUnit, SQL Server Integration Services.

Intern, Software Engineer

IHS
Software engineer developing internal and client-facing distributed systems, including taxonomy management, economic simulation, and forecasting applications. Contributed to the architecture and implementation of distributed backend components, SOAP APIs, and message-based integrations. Designed SQL Server schemas and stored procedures. Built WPF desktop applications with complex data grids and charts. Promoted TDD, SOLID principles, and engineering practices within the team. Technologies: C#, WPF, WCF, MSMQ, NServiceBus, IBM WebSphere MQ, SQL Server, TeamCity, PowerShell, MarkLogic.

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