Serhii

Serhii Bonislavskyi
Backend & Desktop Developer
[open contact info](look above in the "contact info" section) [open contact info](look above in the "contact info" section)

Software Engineer with 4 years of commercial experience specializing in C#/.NET backend development, domain-driven
financial workflows, and cross-platform desktop UI. Proven track record in building enterprise PEPPOL/OIOUBL e-
invoicing pipelines, scalable high-performance web APIs, and desktop applications using Avalonia UI. Focused on clean
architecture, dynamic data models, and business impact.

CORE TECHNOLOGIES

LANGUAGES & CORE DATA & STORAGE ARCHITECTURE & PRACTICE
C#, .NET, ASP.NET Core, LINQ, SQL, MS SQL, Entity Framework Core MVVM, SOLID, Clean Architecture,
Avalonia UI, XAML REST APIs

COMMERCIAL EXPERIENCE

C# Back-end & Desktop Developer Jan 2022 — Mar 2026
Consultloc A/S – Denmark (Remote)
TechStack:C#,.NET,ASP.NETCore,EFCore, SQL, MS SQL, Avalonia UI, XAML, OpenXml, xUnit

• Integrated PEPPOL and OIOUBL e-document workflow systems, replacing manual invoicing processes and fully
automating B2B/B2G compliance for a platform handling up to 5,000 financial documents per day.
• Designed and scaled an end-to-end financial document lifecycle system (invoices, commercial proposals), supporting
over 8,000 monthly active users without long-term downtime.
• Optimized document processing pipelines using OpenXML, achieving sub-second Word/Excel report generation for large-
scale data exports while maintaining complex layout styling.
• Structured and optimized the database access layer using EF Core and MS SQL, ensuring high query elasticity and fault
tolerance during peak daily document creation loads.
• Implemented integration and unit test suites for critical business logic, achieving over 85% code coverage and completely
eliminating financial billing regressions in a production environment.

C# Desktop Developer Dec 2025 — Apr 2026
Par t-time
TechStack:C#, Avalonia UI, XAML, MVVM, SOLID

• Developed a cross-platform desktop application (Avalonia UI) for youth martial arts competitions, completely replacing
paper match logging with real-time digital score and penalty tracking.
• Engineered an automated match protocol generator that automatically compiles and exports structured Word documents
for instant reporting and record-keeping.
• Implemented real-time penalty calculation formulas and precise audio warning countdown triggers, minimizing referee
timing errors and streamlining overall tournament pacing.

EDUCATION LANGUAGES

Diploma in Computer Science • English: Professional / Working Proficiency
Borys Grinchenko Kyiv University
• Ukrainian: Native
2020 — 2024
• Russian: Fluent