I'm a .NET Backend Developer with 1.5 years of commercial experience — I shipped production REST APIs in C#/.NET at Unmanned Systems Poland, working on a modular monolith with Clean Architecture, Hexagonal Architecture, DDD and CQRS, integrating systems like Keycloak, Apache Pulsar, RabbitMQ and Matrix, running code reviews, and mentoring a new team member.

Outside of backend engineering I teach programming (C++, C#, Python, cybersecurity) at Giganci Programowania, tutor students privately in mathematics and programming, and I'm finishing a Master's in Computer Science at Lublin University of Technology.

I learn fastest when I'm building — most of what's below exists because I wanted to understand how something actually works in production, not just in a tutorial.

Currently learning: cloud architecture, Kubernetes, distributed systems design.

A multi-module platform for organisation and team management at Unmanned Systems Poland, integrated with AI capabilities. (Proprietary — code not public.)

Built on a modular monolith with Clean Architecture, Hexagonal Architecture, DDD and CQRS. Inter-module communication goes through Apache Pulsar event contracts; authorisation is delegated to Keycloak. I independently designed and shipped Hub — a satellite forum microservice with its own PostgreSQL instance, REST API, and independent deployment pipeline.

Day-to-day responsibilities

• Designing new modules end-to-end: contracts, persistence, tests, deployment
• Integrating external systems (Keycloak, Pulsar, MCP tooling for AI)
• Running code reviews, mentoring new hires, writing technical documentation
• Presenting technical progress to international investors

Stack: C# · .NET · PostgreSQL · Apache Pulsar · RabbitMQ · Keycloak · Matrix · Docker · GitLab CI/CD

🔧 Internal utilities I developed to speed up day-to-day backend work

Small internal tools I designed and implemented to make testing, debugging and integration work less painful for the whole team.

Scenario tester — reproducible end-to-end test scenarios across modules	MCP test tool — manual harness for MCP server / AI tool integration
Pulsar events tool — inspect, replay and diff event contracts	Module activity diagram — documentation output for module flows

Each project below represents a deliberate engineering decision, not a tutorial follow-along. Click any section to expand full details.

A REST API for todo management, deliberately built past "CRUD demo" quality. What makes it interesting is not the feature set — it's the choices: integration tests hit a real PostgreSQL via Testcontainers, a custom token-bucket rate limiter returns proper Retry-After headers, Polly handles transient failures with exponential back-off, and the GitHub Actions pipeline runs CodeQL security scans and publishes Docker images on every push to main.

Stack: .NET 8 · PostgreSQL · Testcontainers · Polly · xUnit · Docker · GitHub Actions

Backend for an end-to-end e-learning platform: course authoring, purchase with virtual currency, reviews, and a four-tier role hierarchy (User → Verified → Teacher → Admin). JWT access + refresh tokens, Caffeine caching on hot paths, brute-force protection via failed-attempt tracking, and SMTP-based email verification. Courses support chapters, subchapters, quizzes, video, and images — the real-world data model, not a stripped-down demo.

Stack: Java 22 · Spring Boot 3.3 · Spring Security + JWT · PostgreSQL · Hibernate · Caffeine · Docker

Frontend: React application by Hubert Ozarowski

More screenshots — Swagger, ERD, tests

REST API (Swagger)	ERD diagram
Test suite

Geospatial clustering of Warsaw's real estate market using authentic district boundaries from OpenStreetMap — not rough rectangles. The core is a custom "manual stitching" algorithm that assembles precise 18-district polygons from raw OSM boundary segments. Synthetic listings are generated inside real polygons (validated with polygon.contains()), then clustered with K-means where k is selected automatically via the Silhouette + Elbow methods. Output is a set of interactive Folium maps with toggleable layers, heatmaps and centroids.

Stack: Python · Scikit-learn · GeoPandas · Shapely · Folium · Overpass API

18 districts reconstructed from OSM	K-means clusters on the real map
Price-density heatmap	Generated report overview

Full-stack SPA for analysing residential real estate prices across 17 Polish cities using official NBP data (Q3 2006 – Q4 2023). Interactive ApexCharts visualisations, side-by-side city comparisons, primary vs secondary market segmentation, and housing prices plotted against NBP reference rates for macroeconomic context. Data export in JSON and XML, authentication via Laravel Sanctum.

Stack: Angular 17 · TypeScript · Laravel 10 · PHP 8.2 · MySQL · ApexCharts · Docker

Interactive personal portfolio built with React, TypeScript and Tailwind CSS. Features a 3D project showcase, bilingual UI (PL/EN), dark/light theming, and live data from the GitHub API — so the projects and stats shown there stay in sync with this profile automatically.

Home — GitHub Pages	About — 3D project showcase
Bilingual	Light theme

Stack: React · TypeScript · Tailwind CSS · GitHub Pages · GitHub API

Dec 2024 — Mar 2026 · Remote

• Designing and shipping modules in a modular monolith (Clean Architecture, Hexagonal Architecture, DDD, CQRS)
• Integrating external systems: Keycloak, Apache Pulsar, RabbitMQ, Matrix, MCP tooling for AI
• Independently delivered Hub — a satellite forum microservice, full REST API, own DB, own pipeline
• Running code reviews, mentoring a new team member, writing technical documentation
• Presenting technical progress to international investors

Jul 2024 — Present · Remote

• Long-form C++, C# and Python courses for teenage students
• Cybersecurity fundamentals
• Managing groups of 8–12 students and adapting pace to skill level
• Demo lessons (C#, Python) for prospective clients

2019 — Present

Tutoring taught me how to explain a single concept five different ways until something clicks, how to write instructions that won't be misread, and how patient debugging works when the person in front of you is stuck. Skills I still rely on every day in code review and documentation.

Tutoring taught me how to explain a single concept five different ways until something clicks, how to write instructions that won't be misread, and how patient debugging works when the person in front of you is stuck. Skills I still rely on every day in code review and documentation.

Certifications

Certificate	Issuer
Reactive Architecture: Reactive Microservices	Cognitive Class
Reactive Architecture: Domain-Driven Design	Cognitive Class
Introduction to Cybersecurity	Cisco Networking Academy
Basics of C++	Sololearn

• Pursuing M.Sc. in Computer Science at Lublin University of Technology
• Teaching C#, Python and cybersecurity at Giganci Programowania
• Tutoring students privately in mathematics and programming
• Open to new backend engineering opportunities