Олександр

Olexandr Hutsul
.NET Developer
Lublin, Poland · [open contact info](look above in the "contact info" section) · [open contact info](look above in the "contact info" section)
GitHub · LinkedIn · Telegram

SUMMARY

.NET developer building production-style Web APIs with ASP.NET Core and EF Core. Strong with Clean/Onion
architecture, JWT authentication, database transactions, unit testing, and containerizing apps with Docker. Ships
full-stack projects with React/TypeScript frontends and real database workflows.

SKILLS

Language: C#
Backend: ASP.NET Core, Web API, REST, LINQ, Async/Await, CancellationToken, Serilog, Global Exception
Handling (ProblemDetails / RFC 7807)
Database: PostgreSQL, SQL Server, EF Core, Migrations, Relationships, Eager Loading
Caching: Redis (StackExchange.Redis, IDistributedCache), cache-aside with TTL and invalidation
Real-time: SignalR (WebSockets, hubs, presence, typing)
Auth & Security: JWT Bearer, Refresh Tokens, BCrypt, Claims & Role-based Authorization, Permission/Role-based
access control, IDOR protection, 403 vs 401 semantics
Architecture: Onion / Clean Architecture, Domain Services, Unit of Work, Repository, DTOs, AutoMapper,
Dependency Injection, Layered
Reliability: Database Transactions (ACID), Optimistic Concurrency (RowVersion), Idempotency, Background
Services (IHostedService / BackgroundService), Rate Limiting, Health Checks, Graceful Degradation
Testing: xUnit, Moq, FluentAssertions, Integration Testing (WebApplicationFactory)
DevOps: Docker, Docker Compose, Azure (SQL Database, App Service), CI/CD (GitHub Actions), Railway,
Cloudinary (media storage)
Tooling: FluentValidation, Swagger, Postman, Rider, Git / GitHub
Frontend: React, TypeScript, Vite, PWA
PROJECTS

Loom — Real-time Messenger (Full-Stack) github.com/LaGretta/Loom
Live demo: sweet-tranquility-production.up.railway.app
Full-stack real-time messenger on .NET Clean/Onion Architecture — direct chats, groups and channels with live
messaging, a virtual-currency economy (stars, gifts, premium), and shareable calendar events with RSVP. React PWA
client, deployed live on Railway.
• Real-time messaging over SignalR — live delivery, presence and "last seen", typing indicators, and live
propagation of edits, reactions, read receipts and pinned state; graceful reconnect with silent resync
• JWT auth with rotating refresh tokens and silent client-side refresh; role-based group permissions
(Owner/Admin/Member) with IDOR protection and correct 403 vs 401 semantics
• Virtual economy with atomic star transactions (Unit of Work + DB transactions) — gifts, premium subscriptions and
a full star ledger, with rollback on failure
• Calendar events shared into chats with RSVP and live attendee counts; invite links with expiry, usage limits and
revocation
• Background services (IHostedService) for expired-token cleanup and stale-presence reconciliation; Redis
cache-aside for hot read paths with TTL and invalidation, degrading to direct DB reads when Redis is absent
• Production hardening: rate limiting, health checks with DB probe, global exception handling (RFC 7807), voice
messages and media via Cloudinary, offline message queue with retry

• Service-layer unit tests (xUnit, Moq, FluentAssertions); fully containerized with Docker Compose and deployed live
on Railway
Tech: C# · .NET · ASP.NET Core Web API · EF Core · PostgreSQL · Redis · SignalR · JWT + Refresh Tokens · Background
Services · Rate Limiting · Health Checks · AutoMapper · FluentValidation · Serilog · xUnit · Moq · FluentAssertions · Clean
Architecture · REST · Docker · Docker Compose · Cloudinary · Railway · React · TypeScript · PWA
Nova — Digital Banking Platform (Full-Stack) github.com/LaGretta/NovaBank-App
Full-stack digital bank on Clean / Onion Architecture — multi-currency accounts, cards, transfers, savings, annuity
loans, currency exchange and analytics, with a React PWA client.
• Atomic money movement via Unit of Work + database transactions with idempotency keys and optimistic
concurrency (RowVersion) — all-or-nothing transfers, top-ups, loan and savings payments
• JWT authentication with rotating single-use refresh tokens and silent client-side token refresh; role claims (User /
Admin)
• Annuity loan engine with a full amortization schedule; cross-currency transfers using live NBU exchange rates with
in-memory caching
• ~29 service-layer unit tests (xUnit, Moq, FluentAssertions); fully containerized with Docker Compose (API + SQL
Server + frontend, one command, EF migrations auto-applied on startup)
Tech: C# · .NET · ASP.NET Core Web API · EF Core · SQL Server · JWT + Refresh Tokens · AutoMapper · FluentValidation
· Serilog · xUnit · Moq · FluentAssertions · Clean Architecture · REST · Docker · Docker Compose · React · TypeScript · PWA
LinguaFlow — English Learning Platform (SaaS) github.com/LaGretta/Lingua
Full-stack English-learning app on Clean / Onion Architecture — structured courses (A1–C2), interactive exercises
and a spaced-repetition engine, with gamification and a freemium model.
• Designed the SM-2 spaced-repetition algorithm and a streak system as pure domain services, fully unit-tested
(xUnit, Moq, FluentAssertions)
• Secure REST API with JWT authentication and role-based authorization (User / Admin) — Repository + Unit of
Work, DI, AutoMapper, FluentValidation
• EF Core + SQL Server domain — code-first migrations, entity relationships with cascade/restrict rules, unique
constraints, seeding
• Serilog structured logging, global exception handler (RFC 7807 ProblemDetails), freemium per-user daily limits
Tech: C# · .NET · ASP.NET Core Web API · EF Core · SQL Server · JWT · AutoMapper · FluentValidation · Serilog · xUnit ·
Moq · FluentAssertions · Clean Architecture · REST · React · TypeScript · PWA

EDUCATION

• Ternopil Ivan Puluj National Technical University — Bachelor’s in Software Engineering (in progress)
• IT STEP Computer Academy (2023–2025) — Professional Diploma in Software Development (backend with C#
and ASP.NET Core, databases, authentication, testing)
LANGUAGES

English B2 · Ukrainian / Russian Native · Polish B1

AVAILABILITY

Open to on-site, hybrid or remote · willing to relocate across PL & EU · full-time · immediate start

CURRENTLY LEARNING

CQRS + MediatR · WebRTC · Kubernetes basics