Victor

Victor Kozak
Senior .NET / C# Backend Engineer
PROFESSIONAL SUMMARY
Senior software engineer with 20+ years of experience designing and delivering robust backend systems on the .NET / C#
platform. Track record across healthcare, fintech, travel, media, IoT, and contact-centre domains, building RESTful APIs, real-time
services, cloud-native microservices, and data-intensive pipelines. Experienced in managing the full backend lifecycle from
architecture and database design to CI/CD and production support. Strong collaborator with a history of delivering complex projects
on schedule.

SKILLS
Languages: C# (primary), Managed C++, SQL, PL/SQL, T-SQL, JavaScript / Node.js
Backend: .NET, .NET Core, ASP.NET Core, Web API, SignalR, Entity Framework, Dapper, NHibernate, FHIR
Architecture: Distributed systems, microservices, REST APIs, event-driven, enterprise & desktop applications
Frontend: Blazor, MAUI
Databases: MSSQL, PostgreSQL, MongoDB, Cassandra, Redis, Elasticsearch, SQLite, Amazon QLDB
Cloud / DevOps: Azure, Docker, RabbitMQ, MQTT, Azure DevOps, Git, CI/CD, Jira
Auth / Payments: Identity Server (OAuth / OpenID), Stripe, Dwolla, Apple Pay, Google Pay
Tools: Visual Studio, JetBrains Rider, SSMS, Claude Code, GitHub Copilot, Ollama

EXPERIENCE
Senior .NET Backend Engineer
Cargill - Factory Management (via Five Systems Development) Apr 2025 – Present
• Building a factory management application for chocolate production operations: admin UI plus backend services for production
planning and process optimisation.
• Stack: C#, .NET, MSSQL

Senior .NET Backend Engineer
ATPI - Travel & Event Solutions (via Five Systems Development) Dec 2024 – Apr 2025
• Architected and developed backend services and REST APIs for a global corporate travel and event management platform
operating across 120+ countries and multiple specialist sectors (marine, energy, sports).
• Improved service reliability and optimised data access for large booking datasets.
• Stack: C#, .NET, MSSQL

Senior .NET Backend Engineer
AiLuvio - Real-Time Video Dubbing (via Five Systems Development) Aug 2024 – Dec 2024
• Designed low-latency backend services supporting real-time AI-powered audio/video dubbing during live calls.
• Integrated cloud media pipelines on Azure and aligned API contracts with frontend engineers.
• Stack: C#, .NET Core, MSSQL, EF, Azure, Node.js

Senior .NET Backend Engineer
Elott - Media Platform (via Five Systems Development) Jun 2023 – Aug 2024
• Built and maintained backend services for a media streaming platform.
• Used Amazon QLDB for an immutable audit ledger and Elasticsearch for full-text content search, significantly reducing query
latency.
• Stack: C#, .NET Core, MSSQL, EF, Amazon QLDB, Elasticsearch, Docker

Senior .NET Backend Engineer
Resolve Biosciences - Carl Zeiss Microscope Station (via Five Systems Development) Mar 2023 – Jun 2023
• Backend services and APIs for a scientific image-acquisition station integrated with Carl Zeiss microscopy hardware (Molecular
Cartography spatial transcriptomics).
• Used OpenCV for image pre-processing and MQTT for real-time device communication in containers.
• Stack: C#, Docker, SQLite, OpenCV, MQTT

Senior .NET Backend Engineer
Powersoft - Stock Management System (via Five Systems Development) Dec 2022 – Mar 2023
• Full-stack backend services and REST APIs for an inventory management solution: business logic for stock tracking, alerting,
and reporting modules.
• Stack: C#, .NET Core, MSSQL, EF, Blazor, DevExpress
Senior .NET Backend Engineer
SPSoft - Healthcare COVID-19 Platform Oct 2021 – Dec 2022
• Backend services for processing COVID-19 vaccine administration and test result workflows, fully compliant with HL7 FHIR.
• Ensured data integrity and secure data exchange between healthcare providers on Azure.
• Stack: C#, .NET Core, MSSQL, EF, Azure, Blazor, FHIR, Azure ML
Senior .NET Backend Engineer
OnWallet - Multi-Currency Wallet System (via Five Systems Development) Aug 2021 – Oct 2021
• Designed high throughput microservices for a multi-currency digital wallet, integrating Dwolla ACH transfers and Stripe
payments.
• Used SignalR for real-time balance notifications and RabbitMQ for reliable event-driven communication.
• Stack: C#, .NET Core, SignalR, Docker, Identity Server, Redis, Elasticsearch, Cassandra, RabbitMQ, Dwolla, Stripe, AWS

Senior .NET Backend Engineer
Dynamiti - CRM Deployment Portal (via Five Systems Development) Aug 2021 – Sep 2021
• Backend services for a SaaS CRM deployment portal, including subscription billing via Stripe and automated provisioning
pipelines on Azure.
• Stack: C#, .NET Core, Docker, MSSQL, EF, Stripe, Azure

Senior .NET Backend Engineer
Questrade - Financial Services Platform (via N-iX) Nov 2020 – Jul 2021
• Backend services for Canada's largest independent online brokerage ($50B+ AUM): account data pipelines and trade-related
microservices, maintaining the high availability standards required for financial-grade applications.
• Stack: C#, .NET Core, MongoDB, Node.js, Docker

Senior .NET Engineer
NICE Systems - Air & Engage Platform (via Delphi Software) Apr 2019 – Nov 2020
• Media playback and routing services for NICE Systems' contact-centre engagement platform.
• Used RabbitMQ to decouple media processing pipelines, improving throughput and fault tolerance.
• Stack: C#, .NET Core, RabbitMQ

Senior .NET Engineer
Omnitracs - Fleet Management (via Ciklum) Jan 2019 – Apr 2019
• Extended server-side services for a leading fleet telematics platform; optimised NHibernate queries and added new reporting
capabilities.
• Stack: .NET Framework, C#, MSSQL, NHibernate

Senior .NET Developer
212Dentalcare - Dental Practice Portal (via Leale Solutions) Jul 2018 – Jan 2019
• Web portal and backend API for a dental practice management system: appointment scheduling, patient records, and Twilio-
powered SMS / voice reminders.
• Stack: ASP.NET Core, C#, MSSQL, Web API, React, Redux, EF, Dapper, Twilio

EARLIER EXPERIENCE
2003 – 2018 — Senior / Lead .NET Developer roles across fintech (Finova Financial), healthcare (IMG Healthcare), CMS /
corporate portals, fuel POS (Wincor Nixdorf NAMOS), pharma (Parexel), CRM (Glaux Soft EvidenceXP), enterprise call recording
(NICE Systems Perform), and ERP (Softline Megapolis2). Roles included Team Lead and Technical Leader. Stacks included C#,
.NET Framework, ASP.NET MVC / Web API, AngularJS, MSSQL, Oracle, PostgreSQL, Cassandra, Redis, VC++ / ATL.

EDUCATION
Bachelor’s Degree in Banking & Finance — State University of Trade and Economics, 1998

LANGUAGES
Ukrainian (native) · English B1 (intermediate)