C# / .NET / Software architecture

Welcome to my
developer website.

I'm Sergey Matvienko, a senior .NET developer and software architect based in St. John's, Canada.

I build practical software, solve complex application problems, and care about keeping code clear and maintainable.

A little about me My Stack Overflow profile
Sergey Matvienko outdoors
Sergey Matvienko St. John's, Canada
Building software. Sharing knowledge.

25+ yearsof software development experience

C# gold tag badgeon Stack Overflow

3,200+ answerscontributed to Stack Overflow

01 / About me

Experience built
through real work.

From established enterprise systems to new applications, I enjoy making software work well for the people who use it.

My background covers more than 25 years in software development, including extensive work with C# and the Microsoft .NET ecosystem. I've worked across Canadian federal government, SaaS, municipal government, and insurance environments.

I work across the development lifecycle: understanding requirements, designing applications and databases, implementing and testing solutions, and supporting deployment. My main areas include ASP.NET Core, Web APIs, SQL Server, Entity Framework Core, and application authorization.

I also enjoy helping other developers. My Stack Overflow contributions focus on practical C# and .NET questions, especially JSON, ASP.NET Core, and Entity Framework Core.

Regular refactoring is part of how I work. I prefer useful, well-understood tools and clear code that can be maintained over time.

Applications & APIs
C#, .NET, ASP.NET Core MVC, Web APIs, REST, OData
Data & databases
SQL Server, Entity Framework Core, Oracle, data migration, query tuning
Interfaces
Angular, TypeScript, Razor, WPF, MVVM
Engineering
Application architecture, authorization, asynchronous programming, TPL, testing, refactoring

02 / Selected experience

A few places I've worked.

Hands-on development, architecture,
and problem solving.

  1. 2023–2025

    The Governor General of Canada

    Programmer Analyst Level 3

    Architecture and development of enterprise applications with ASP.NET Core, Angular, Web APIs, and SQL Server.

  2. 2022–2023

    Global Affairs Canada

    Programmer Analyst Level 3

    Asynchronous .NET applications, service integration, and database migration.

  3. 2018–2022

    Focus

    Senior .NET Developer

    SaaS applications, including identity and authorization management.

  4. 2016–2017

    Senate of Canada

    Programmer Analyst Level 3

    Web applications, database development, reporting, and application integration.

03 / Personal projects

What I'm working on.

Independent projects, built and improved over time.

In development

Permission administration library

A reusable .NET library for administering users and permissions, designed for integration into other software applications.

C# / .NET

Being updated

Triangle Ball Solitaire

A small puzzle game originally created to explore the journey from development to publication. I'm updating the desktop version before preparing a browser version.

C# / Unity

04 / Get in touch

Let's talk about software.

For .NET development opportunities, project discussions, or a technical conversation, you're welcome to contact me.

[email protected] St. John's, Newfoundland & Labrador, Canada Find me on Stack Overflow