Károly Ozsvárt

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

Location: Budapest, Hungary
Contact: karoly-ozsvart.static115@simplelogin.com
Links: Online CV · LinkedIn · GitHub · GitLab · YouTube · Stack Overflow

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 (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 book.
  • Competition winner — 15+ professional programming competitions, several wins.
  • Content creator — Hungarian C# tutorial series on YouTube.
  • Open source — most of my personal code is public: see it all.

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.