# Károly Ozsvárt
> Staff Software Engineer · C# .NET Backend · AWS & Azure · Maintainability-first

**Location:** Budapest, Hungary  
**Contact:** [karoly-ozsvart.static115@simplelogin.com](mailto:karoly-ozsvart.static115@simplelogin.com)  
**Links:** [Online CV](https://arphox.github.io/cv/) · [LinkedIn](https://www.linkedin.com/in/arphox/) · [GitHub](https://github.com/arphox) · [GitLab](https://gitlab.com/arphox) · [YouTube](https://www.youtube.com/@ozsvartkaroly) · [Stack Overflow](https://stackoverflow.com/users/4215389)

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## Summary

C# / .NET backend engineer since 2017, currently **Staff Engineer / Team Architect** on an AI-enhanced, video-based e-learning platform. I design and build backend services and Web APIs — currently on AWS, earlier on Azure — and what I care about most is **maintainability**: clean code, solid tests, and an architecture that stays easy to change as teams and traffic grow. I set technical direction across teams, mentor engineers and share knowledge, and keep technical debt under control. I lean on automation to keep quality high by default, and work transparently — giving and inviting feedback openly.

## Core skills

- **Languages & runtime:** C# (since 2017), modern .NET (through .NET 10), .NET Framework
- **Backend:** ASP.NET Core Web API, REST, distributed & event-driven systems, microservices
- **Cloud:** AWS (Lambda, ECS/Fargate), Azure (App Service, Functions)
- **DevOps:** basics of CI/CD, Docker, Terraform
- **Data & storage:** NoSQL-first: DynamoDB (current), Cosmos DB (prior); object storage (S3, Blob); SQS. Earlier MSSQL (+ EF)
- **Testing & quality:** xUnit / TUnit / NUnit / MSTest, Moq / NSubstitute, FluentAssertions, BenchmarkDotNet, Roslyn analyzers
- **Ways of working:** maintainability, automated quality checking, code review, TDD, clean code, SOLID/CUPID
- **Leadership:** technical leadership, mentoring & knowledge-sharing, work breakdown & backlog management (Jira), prioritization & estimation, cross-team alignment
- **AI-assisted development:** daily driver — Claude Code, Cursor, GitHub Copilot
- **Tooling:** Rider, Visual Studio, Git, Postman, dotTrace / dotMemory

## Experience

### Nexius Learning (now Bitwit) — Budapest, Hungary
_AI-enhanced, video-based e-learning platform · C# .NET microservices_

**Staff Engineer (.NET)** · 2024-08 – Present
- Provide technical leadership for the platform backend on a microservices architecture (AWS: Lambda, ECS/Fargate, DynamoDB, S3; Terraform; C# .NET) — architectural guidance, mentoring, and hands-on delivery.
- From 2025-03 to 2026-06, also led the backend-heavy **platform team** (4 engineers) as **Technical Lead / Team Architect**, owning the long-term maintainability, stability and scalability of ~30 backend services — until the backend sub-teams merged back into a single team.
- Break down product goals into well-scoped, estimated backlog items and manage the team's backlog through delivery (Jira).
- Set the team's quality bar with a build-enforced baseline (analyzers, warnings-as-errors, formatting, Git hooks) so violations are caught mechanically and code review can focus on design — keeping technical debt in check as the team grows.
- Drive engineering culture beyond my own team: **founded and run** an internal engineering **book club** (since 2024-08, 4+ books) and **organize a company-wide backend guild** (since 2023-12) that aligns backend practices across teams.
- Contributed to cost-optimization work that cut the platform's AWS bill by ~$3,000/month.

**Tech Lead / Team Architect** · 2023-05 – 2024-08
- Owned the technical direction of the module: supported the product owner with prioritization and estimation, coordinated tasks across the team, and managed technical debt.
- Authored the company-wide **Git standards** largely single-handedly — a thorough, high-quality guideline that raised engineering consistency across teams.
- Designed the backend foundation of the platform's new content-publication model, then refined it with a partner team.
- Helped drive the team's adoption of AI-assisted development (GitHub Copilot and others) — wrote guidance and supported colleagues in integrating it into their workflow.

**Senior C# Backend Developer** · 2022-01 – 2023-05
- Built Web APIs on **.NET 6 / C# 9** in an Azure cloud-first architecture (Cosmos DB, App Service, Azure Functions, Blob Storage), serving learning content and automated test assessment to learners on the platform.

_Employed through VividMind Zrt. until 2024-01._

### Betsson Group — Senior C# Backend Developer · 2021-04 – 2022-01
- Delivered features in the C# .NET backend (Framework 4.7.x and Core 3.1) powering betsson.com and other brands.
- Worked in a multinational, cross-located team; adopted Couchbase, Consul, TeamCity and Octopus.

### Grape Solutions — C# Backend Developer · 2019-07 – 2021-04
- **2020-07 – 2021-04:** Developed an internal product in a microservices architecture (ASP.NET Core 3.1, C# 8, Kafka, MongoDB, Elasticsearch, Redis); owned and maintained an internal NuGet package.
- **2019-07 – 2020-07:** Built core backend Web APIs for **WizzAir.com** (.NET Framework, SQL, EF) in a service-oriented architecture.

### evosoft — C# Backend Developer · 2018-04 – 2019-07
- Developed an internal component of a massive industrial-automation desktop application: TIA Portal — one of the largest C# codebases in the world.
- Sharpened software design and C# performance skills; worked in Scrum with TFS.

### DGITAL Labs — Junior C# Backend Developer · 2017-06 – 2018-04
- Built the backend of a flight-industry website (ASP.NET Web API, C#, Oracle/MSSQL, EF, Elasticsearch, Redis, Hangfire); first exposure to Swagger and CI/CD pipelines.

### Athéné Szakgimnázium — Programming Teacher (C# & theory) · 2015-12 – 2017-05
- Taught programming to ~60 students; built an application for submitting test solutions over the school network.

## Selected achievements

- **Conference speaker** — "C#-based Git hooks" at [BeerUP Tech Fest 2024](https://www.youtube.com/watch?v=wfpaFQ7iZCs) (recorded), on an in-house C# Git-hook framework I architected and co-built.
- **Pro Git contributor** — got a pull request merged into the official [Pro Git](https://git-scm.com/book) book.
- **Competition winner** — 15+ professional programming competitions, [several wins](https://itmap.hu/harom-versenyzo-harom-gyoztes-harom-ujraindulo/).
- **Content creator** — [Hungarian C# tutorial series](https://www.youtube.com/@ozsvartkaroly) on YouTube.
- **Open source** — most of my personal code is public: [see it all](https://gitlab.com/users/arphox/groups).

## Education

- **BSc in Engineering of Information Technology** (mérnökinformatikus), **Óbuda University** — specialization in enterprise information systems.
- **English** — B2 certified; ~B2–C1 in speech and writing.
- **Networking coursework** — Cisco CCNA, MTA Networking Fundamentals.
- **Conferences & courses** — Craft conference attendee (2019, 2024, 2025); regular technical courses and professional reading.

## Interests

Piano 🎹 · books 📖 · video games 🎮 · continuous learning.