Constantin Kotsarenko

Presenting

ConstantinKotsarenko

Senior .NET Developer

Architect of resilient, high-performance systems in C# and the .NET platform — engineered with precision, built to endure.

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Enter
Act I

The Prologue

For more than a decade I have built software on the .NET platform — from the days of the classic Framework to today's cloud-native .NET 8 and 9. I design and deliver backend systems where reliability is not a feature but a promise: payment flows, logistics engines and enterprise platforms that serve millions of requests a day.

My craft lives at the intersection of clean architecture and pragmatic delivery. I favour domain-driven design, well-defined service boundaries and an honest test suite, and I enjoy turning tangled legacy monoliths into elegant, observable, independently deployable services.

Beyond the code, I mentor engineers, lead design reviews and partner with product owners to translate ambition into architecture. Based in Jaworzno, Poland, I collaborate with teams across Europe and beyond.

0
Years in .NET
0
Systems Shipped
0
Engineers Mentored
0
Uptime Delivered

“Software, like architecture, should be beautiful in its structure and unshakeable in its foundations.”

Act II

The Repertoire

The Language

  • C# 12 & .NET 8 / 9
  • ASP.NET Core & Minimal APIs
  • LINQ & async / await
  • Blazor & Razor Pages
  • gRPC & SignalR

The Architecture

  • Domain-Driven Design
  • Microservices & CQRS
  • Event Sourcing
  • MassTransit & RabbitMQ
  • Clean / Hexagonal

The Data

  • SQL Server & T-SQL
  • Entity Framework Core
  • PostgreSQL & Dapper
  • Redis & Caching
  • Cosmos DB

The Stage

  • Microsoft Azure
  • Docker & Kubernetes
  • Azure DevOps & GitHub Actions
  • OpenTelemetry & Serilog
  • xUnit, NUnit & TDD
Act III

The Grand Works

I

Meridian Payments Gateway

Lead Architect · FinTech

Re-engineered a monolithic card-processing platform into twelve event-driven microservices on ASP.NET Core and Azure Kubernetes Service. Introduced the outbox pattern, idempotent consumers and end-to-end distributed tracing to guarantee exactly-once settlement.

3.2Mtransactions / day−68%p99 latency0lost payments
.NET 8AKSMassTransitSQL ServerOpenTelemetry
II

Atlas Fleet Logistics Engine

Senior Developer · Logistics

Built a real-time dispatch and route-optimisation engine tracking 9,000 vehicles across Central Europe. SignalR streams live positions to a Blazor control room, while background workers rebalance deliveries using CQRS read models backed by Redis.

9Kvehicles live−14%fuel costs<200msupdates
SignalRBlazorCQRSRedisPostgreSQL
III

Aurelia Insurance Claims Platform

Tech Lead · Insurance

Led a team of seven to migrate a twenty-year-old .NET Framework 4.5 claims system to .NET 8 using the strangler-fig approach — with zero downtime. Delivered a rules engine for automated claim triage and a modern REST/gRPC API surface for partner integrations.

60%claims auto-triaged5×faster releases0hdowntime
Strangler FiggRPCEF CoreAzure FunctionsxUnit
IV

Sentinel Observability Toolkit

Creator · Internal Open Source

Authored a set of NuGet packages that give every service structured logging, health checks, metrics and resilience policies out of the box. Adopted by over 30 internal teams, it cut new-service bootstrap time from days to under an hour.

30+teams adopted<1hservice bootstrap
NuGetPollySerilogSource Generators
Act IV

The Chronicle

2021 — Present
Remote · Poland

Senior .NET Developer & Tech Lead

Meridian Financial Technologies
  • Own the architecture of the core payments domain across 12 production services.
  • Lead a cross-functional squad of seven; run design reviews and engineering guilds.
  • Drove migration to .NET 8 and AKS, reducing infrastructure spend by 31%.
2018 — 2021
Katowice · Poland

Senior Software Engineer

Atlas Logistics Group
  • Built real-time fleet tracking with SignalR, Blazor and Redis-backed read models.
  • Introduced TDD and CI/CD pipelines in Azure DevOps; coverage rose from 22% to 84%.
2015 — 2018
Kraków · Poland

.NET Developer

Aurelia Insurance Solutions
  • Developed claims-processing modules in ASP.NET MVC and WCF on SQL Server.
  • Optimised critical stored procedures, cutting nightly batch runtime by half.
2013 — 2015
Kraków · Poland

Junior C# Developer

Brightline Software House
  • Delivered WinForms and WPF line-of-business applications for regional clients.
Act V

The Invitation

You are cordially invited to collaborate with

Constantin Kotsarenko
Senior .NET Developer
Residence
Harcerska 8
Jaworzno - 43617
Poland
Telephone
+1 667 321 9295
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Available for senior, lead & architecture engagements