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Hi, I’m Mateusz Smarzyk, a senior .NET engineer based in Lodz, Poland. I design scalable, resilient backend systems using ASP.NET Core, microservices, and cloud-native technologies to help fintech, e-commerce, healthcare, real estate, and automotive domains move fast. I have 10 years of experience delivering high-performance APIs, domain-driven design, and automated CI/CD pipelines, and I enjoy collaborating with cross-functional teams to translate complex business requirements into reliable software.…Hi, I’m Mateusz Smarzyk, a senior .NET engineer based in Lodz, Poland. I design scalable, resilient backend systems using ASP.NET Core, microservices, and cloud-native technologies to help fintech, e-commerce, healthcare, real estate, and automotive domains move fast. I have 10 years of experience delivering high-performance APIs, domain-driven design, and automated CI/CD pipelines, and I enjoy collaborating with cross-functional teams to translate complex business requirements into reliable software.

Mateusz Smarzyk

Back-End Developer, Full Stack Developer, Web Developer, +2

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Hi, I’m Mateusz Smarzyk, a senior .NET engineer based in Lodz, Poland. I design scalable, resilient backend systems using ASP.NET Core, microservices, and cloud-native technologies to help fintech, e-commerce, healthcare, real estate, and automotive domains move fast. I have 10 years of experience delivering high-performance APIs, domain-driven design, and automated CI/CD pipelines, and I enjoy collaborating with cross-functional teams to translate complex business requirements into reliable software.…Hi, I’m Mateusz Smarzyk, a senior .NET engineer based in Lodz, Poland. I design scalable, resilient backend systems using ASP.NET Core, microservices, and cloud-native technologies to help fintech, e-commerce, healthcare, real estate, and automotive domains move fast. I have 10 years of experience delivering high-performance APIs, domain-driven design, and automated CI/CD pipelines, and I enjoy collaborating with cross-functional teams to translate complex business requirements into reliable software.

Available to hire

Hi, I’m Mateusz Smarzyk, a senior .NET engineer based in Lodz, Poland. I design scalable, resilient backend systems using ASP.NET Core, microservices, and cloud-native technologies to help fintech, e-commerce, healthcare, real estate, and automotive domains move fast.

I have 10 years of experience delivering high-performance APIs, domain-driven design, and automated CI/CD pipelines, and I enjoy collaborating with cross-functional teams to translate complex business requirements into reliable software.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Language

English

Fluent

Work Experience

Senior Software Engineer at Wavestone

February 1, 2023 - Present

Designed a microservices architecture using ASP.NET Core 8, Docker, and Kubernetes on AWS EKS, decomposing a legacy platform into 18 bounded contexts for scalable enterprise workflows. Architected domain-driven microservices with Clean Architecture, MediatR, and the outbox pattern to support high-traffic SaaS systems with eventual consistency. Optimized APIs by tuning EF Core 8 queries, adding Redis distributed caching, and enabling async streaming, reducing P99 latency by 68%. Increased throughput for real-time backend APIs by 4x using .NET 8 minimal APIs and low-allocation techniques. Implemented OAuth2/OpenID Connect for multi-tenant security. Automated CI/CD with GitHub Actions, Docker, Helm, and Kubernetes. Implemented observability with Serilog, OpenTelemetry, and Grafana. Deployed to AWS ECS Fargate with RDS Aurora and CloudWatch alarms, achieving high uptime.

Founding Product Engineer at Lido Finance

December 1, 2020 - January 31, 2023

Led the decomposition of a legacy fintech monolith into 12+ ASP.NET Core 6 microservices with gRPC-based interservice communication. Implemented resilient backend services with ASP.NET Core 6, Polly, RabbitMQ, and Redis, handling millions of daily transactions with circuit breaking and retry policies. Modeled domain events and sagas using MediatR and EventFlow in .NET 6 to ensure consistency across distributed payment and wallet workflows. Optimized EF Core LINQ queries, reducing transaction times by 62%, and cut DB round-trips by 80% via bulk operations. Designed an outbox pattern with EF Core transactional outbox and background publishers. Implemented RBAC with policy-based authorization and claims transformation. Built high-performance aggregation APIs with EF Core projections and Redis caching, reducing latency by 58%. Implemented health checks and graceful shutdown handling. Built integration tests with Testcontainers and xUnit for CI pipelines.

Software Engineer at Zalando

September 1, 2016 - November 30, 2020

Built backend services integrated with commerce frontends using ASP.NET Core 2.2–3.1, enabling autonomy across catalog, checkout, and order management. Implemented ecommerce APIs with C#, EF Core, and SQL Server, supporting product catalog and customer workflows. Reduced API response times by 55% through EF Core query optimization, Redis caching, and minimal projections. Refactored EF Core repositories with the Specification pattern and raw SQL fallbacks for complex joins. Implemented background job processing with Hangfire and PostgreSQL. Designed backward-compatible REST APIs with versioning and created middleware for request logging, correlation IDs, and tenant resolution. Implemented circuit breakers and bulkheads with Polly for resiliency. Adopted CQRS with separate read/write models using EF Core and MongoDB projections. Built automated tests and CI pipelines to reduce regressions.