Sergey

Sergey Bonislavskyi
Backend Developer|Desktop Developer

[open contact info](look above in the "contact info" section) | [open contact info](look above in the "contact info" section)
LinkedIn: [open contact info](look above in the "contact info" section)

SUMMARY CORE SKILLS
Backend and Desktop Developer with 3+ years of commercial Languages & Frameworks: C#, .NET, ASP.NET Core, LINQ
experience building scalable web APIs, financial systems, and Desktop: Avalonia UI, XAML
cross-platform desktop applications. Strong expertise in C#/.NET, Web/API: REST API, JSON, XML
clean architecture (MVVM, SOLID), and performance optimization. Data: Entity Framework Core
Proven experience with government integrations (PEPPOL), Architecture: MVVM, SOLID, Clean Architecture
document processing, and end-to-end feature delivery. Testing: xUnit, Integration Testing, Unit Testing
Tools: Git, Agile Development

EXPERIENCE
C# DESKTOP DEVELOPER | Aug 2025 — Mar 2026
Part-time – Denmark (Remote)
Technologies: C#, Avalonia UI, XAML, JSON

• Developed a cross-platform desktop application for real-time competition match event tracking and management
• Designed a customizable UI system, allowing users to configure layouts and workflows
• Implemented Word document export with preserved styling for official reporting
• Applied MVVM and SOLID principles to ensure modular, maintainable, and scalable architecture
• Improved usability with responsive UI and user-focused design decisions

C#BACK-ENDDEVELOPER | Jan2022— Aug 2024
Consultloc A/S – Denmark (Remote)
Technologies: C#, .NET, ASP.NET Core, EF Core, REST API, XML, JSON, xUnit

• Developed and maintained a financial document management system (invoices, quotes, credit notes, payments), supporting
full billing lifecycle
• Integrated PEPPOL/OIUBL e-document exchange, enabling automated communication with partners and public institutions
• Implemented import/export pipelines for standardized document templates (Word/Excel), improving data exchange efficiency
• Wrote integration and unit tests covering critical financial workflows, increasing system reliability
• Collaborated in an Agile environment, delivering incremental features and improvements

Projects
C# DESKTOP DEVELOPER (Diploma Project) | Jun 2024 — May 2025
Technologies: JavaScript, React, Electron, C#, Avalonia UI, XAML

• Built a cross-platform pixel art editor with drawing tools, layer system, color palette, and export functionality
• Migrated application from Electron (JavaScript) to C# and Avalonia UI, improving performance and native UX
• Designed scalable architecture using MVVM and SOLID principles

EDUCATION LANGUAGES
• English
Borys Grinchenko Kyiv University – Ukraine
• Ukrainian
Diploma in Computer Science (2020 — 2024)
• Russian