Sergiy

SERGIY PONOMARENKO — Senior .NET Backend Developer
Spain (temporarily) / Ukraine · Remote
Email: [відкрити контакти](див. вище в блоці «контактна інформація»)
LinkedIn: [відкрити контакти](див. вище в блоці «контактна інформація»)

SUMMARY
Senior .NET Backend Developer with 9+ years of experience building and maintaining
production backend systems and microservices under load. Strong in ASP.NET Core,
REST APIs, messaging systems, SQL/NoSQL databases, and cloud environments (AWS, Azure).
Experienced in real-time services and event-driven architectures.

TECHNICAL SKILLS
Backend & Frameworks: .NET Core .NET 9/8/6 · Web API · gRPC · EF Core · Dapper
Databases: MS SQL · PostgreSQL · Redis · MongoDB
Messaging & Integrations: RabbitMQ · MassTransit · Kafka · REST · OAuth2/JWT
Cloud & DevOps: AWS · Azure · Docker · GitHub Actions
Tools: Git · Jira · Confluence · Swagger · Postman

PROFESSIONAL EXPERIENCE
Senior .NET Backend Developer — SIEMA (Product Platform) Remote | 2024 — Present
Feature-oriented .NET 9 platform connecting employers and workers.
-Developed and maintained a feature-oriented backend platform connecting employers and workers
using ASP.NET Core (.NET 9).
-Implemented backend services and APIs using Vertical Slice architecture, CQRS, and Wolverine.
-Built and supported core backend modules including Chat, Credits, Notifications, and User
Management.
-Implemented real-time communication using SignalR and domain events.
-Integrated third-party services: AWS S3, Twilio, SendGrid, Quartz.
-Improved system reliability and observability using structured logging and monitoring (Serilog,
OpenTelemetry).
-Supported cloud deployment and CI/CD pipelines using Azure DevOps.

Senior .NET Backend Developer — Treepl (USA, SaaS Platform) · 09/2022–05/2024
-Worked on a SaaS CMS and SSO platform hosted on AWS (EC2, ECS, RDS, ALB, Route 53).
-Migrated legacy .NET Framework applications to .NET 6 microservices.
-Designed and implemented REST APIs and backend services using CQRS and Mediator pattern.
- Integrated RabbitMQ with MassTransit for asynchronous messaging and system integration.
- Improved system scalability, deployment stability, and release automation.
- Maintained CI/CD pipelines and deployment workflows using Azure DevOps.

Senior .NET Backend Developer — Lizard Soft · 08/2020–09/2022
-Developed backend services for a Supervisory Board voting system.
-Migrated a monolithic system to cloud-based microservices on Azure.
-Implemented backend components using ASP.NET Core, Azure Service Bus, Azure Functions, and
Azure SQL.
- Improved system performance, reliability, and maintainability through refactoring and optimization.
- Collaborated closely with frontend and QA teams to deliver production-ready features.

.NET Backend Developer — Agile Fuel (Ukraine) · 09/2019–08/2020
-Developed backend APIs using ASP.NET Core and Clean Architecture principles.
-Improved backend stability and reduced operational costs through refactoring.
-Worked in Agile/Scrum environment delivering features in short iterations.

.NET Developer (Full-Stack) — Applikator (Denmark) · 07/2014–09/2019
-Developed and maintained backend services using .NET Framework 4.7.
-Built and supported REST APIs and database-driven web applications.
-Collaborated with frontend developers on system integration.
- Participated in system design discussions and long-term product maintenance.

EDUCATION & LANGUAGES
Kharkiv National Polytechnic University — Computer Science.

Languages: Ukrainian (Native), English (B2), Russian (Fluent)

KEY ACHIEVEMENTS
-Improved backend reliability and performance in high-load scenarios through async processing
-and optimized data access.
-Participated in migration from monolithic applications to microservices, improving scalability,
deployment flexibility, and fault isolation.
-Improved API performance and response times through profiling, query optimization, and efficient
caching strategies.
-Implemented and maintained CI/CD pipelines, reducing manual deployment errors and improving
release reliability.