Illia

Illia Yarosh
Senior .NET Developer

Ukraine · Remote

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

Professional Summary
Senior .NET Backend Developer with 10+ years of commercial software engineering experience,
including 5+ years in banking and fintech. Proven experience designing and delivering backend
services from scratch, modernizing legacy systems, implementing complex distributed workflows, and
leveraging AI-assisted development tools to improve engineering productivity.

Core Competencies: Full software development lifecycle — from technical design, API
contracts and trade-off analysis to implementation, CI/CD deployment and production support.
Domain Expertise: Payment processing, customer onboarding & actualization, digital signatures
(FOP), credit products, security management and government-service integrations (Diia).

Technical Skills
Backend: C#, .NET, ASP.NET Core, REST API, gRPC, Entity Framework Core (EF Core),
Dapper, LINQ
AI-Assisted Development: Claude, ChatGPT, GitHub Copilot, Google Gemini
Architecture & Patterns: Microservices, Distributed Systems, SOLID, Design Patterns,
Dependency Injection
Data & Caching: Relational Databases (PostgreSQL, MS SQL), NoSQL (MongoDB), Redis
Messaging & Processing: RabbitMQ, MassTransit, Background Services, Quartz.NET
CI/CD & Deployment: GitLab CI/CD, Kubernetes, ArgoCD, Docker, IIS
Testing & Observability: xUnit, Moq, FluentAssertions, ELK/Kibana, Grafana, Dynatrace,
Serilog

Professional Experience

VST Bank / Ornament Soft Solution

Software Engineer — Middle → Senior → Principal .NET Developer
05/2021 – Present

Backend development for a customer-facing banking platform focused on payments, security, customer
onboarding and third-party integrations.

Backend Development: Designed and developed 20+ backend services from scratch, covering
payment processing, digital signatures, credit products and security flows.
System Design: Designed technical solutions, evaluated architectural trade-offs and defined
REST API contracts for web and mobile clients.
Integrations: Integrated internal banking systems and external financial and government
services, including core banking, CRM, Corezoid, Bifit, UPC Gate / Plutus, CardOn, Hermes and
Diia.
Asynchronous Processing: Implemented messaging, distributed state and background
processing across multiple backend services.
Production & Delivery: Participated in code reviews, production troubleshooting, releases and
application deployment using GitLab CI/CD, Kubernetes and ArgoCD.

Key Projects

P2P Transfer Platform

Reworked core P2P transfer functionality practically from scratch, introducing a flow- and
strategy-based architecture supporting card-to-card, phone-number, domestic and cross-border
scenarios.
Integrated UPC Gate / Plutus to determine international transfer availability and route transfers
through the appropriate flow.
Processed 20,000+ completed transfer flows per day during observed production periods.

Digital Signature & FOP Services

Developed a set of services supporting digital-signature workflows for individual entrepreneurs
(FOP), using MassTransit for asynchronous workflows and Quartz.NET for scheduled
processing.
Built a dedicated gRPC service for access to an external Bifit database, isolating the external
dependency from the main application flow.

Security Management Service

Developed an internal security service from scratch for managing customer restrictions across
multiple security scenarios, including repeated incorrect password attempts, device changes,
newly registered users and permanent blocks.
Used Redis for temporary restrictions and persistent storage for long-lived blocks.

Corezoid Multi-step Workflows

Developed a reusable Corezoid integration pattern for multi-step customer workflows, storing the
current flow state so users could resume interrupted actions.
The integration pattern was reused across 20+ services and business flows, including customer
verification, credit limits, password recovery, card reissues, FOP registration and digital
signatures.

Customer Actualization & Diia Integration

Developed a customer actualization service from scratch, enabling customers to update personal
information remotely through the mobile application.
Designed and implemented backend integration with Diia for verified electronic documents and
customer identification, registration and actualization flows.
Integrated Corezoid, CRM, document/photo processing and financial-monitoring services to
support different customer flows and business rules.

Independent .NET Developer

Part-time · Remote
06/2019 – 05/2021

Bulgarian Lawyers Registry

Modernized a production application from legacy ASP.NET to .NET Core 3.1, rebuilding the
backend where a direct migration was not practical; later upgraded the application to .NET 6.
Developed new backend functionality and integrations with Bulgarian public registries.

Automated CMS Provisioning

Developed an automated provisioning solution for a CMS used by kindergartens, schools and
other organizations.
Automated website and database creation, IIS configuration, database users and permissions,
application configuration, subdomain creation and deployment.

Ecoservice

.NET Developer · Remote
06/2018 – 05/2021

Developed ASP.NET Core services for environmental monitoring and GIS platforms, processing
data from approximately 50 physical monitoring stations.
Built a TCP listener for direct station data ingestion, with PostgreSQL/PostGIS, GeoServer,
OpenLayers and GeoJSON used for storage and GIS-based visualization.
Developed background services for data aggregation, anomaly detection, inactive-station
monitoring, alerts and reporting.

AlterEGO LLC

Programmer / Android Developer
06/2016 – 07/2017

Developed an Android application for a social video platform focused on concert and event
videos using Java and REST API integrations.

Education
Donbas State Machine-Building Academy
Master’s Degree in Computer Science · Faculty of Automation and Information Technologies
Kramatorsk · 2013–2019

Certifications
Google AI Professional Certificate
Google · May 2026
AI fundamentals, research, communication, data analysis and app building.
Credential: View certificate

Languages
Ukrainian: Native
English: B1 (Intermediate) — technical documentation and written communication