Sergiy Ponomarenko

I’m a Senior .NET Backend Developer with 9+ years building production systems—from multi-tenant SaaS platforms to real-time microservices with AI integration. I gravitate toward technically complex tasks like distributed systems and event-driven architectures, and I’m at my best when I stay hands-on in code.

At SIEMA (2024–present), I’ve owned and developed core backend modules (Chat, Credits, Notifications, User Management) for a feature-oriented .NET 9 platform. I implemented CQRS and Vertical Slice architecture using Wolverine, built real-time communication with SignalR and domain events, and integrated third-party services including AWS S3, Twilio, SendGrid, and Quartz. I also delivered AI-powered capabilities with AWS Bedrock (Amazon Nova) and OpenAI APIs, including embedding-based vector search and LLM-driven query refinement, and I’ve focused on observability with Serilog and OpenTelemetry while maintaining CI/CD via Azure DevOps.

Previously at Treepl (09/2022–05/2024), I worked on a SaaS CMS and SSO platform hosted on AWS. I migrated legacy .NET Framework applications to .NET 6 microservices to improve deployment flexibility and resilience, and I designed REST APIs using CQRS and the Mediator pattern. I integrated RabbitMQ with MassTransit for asynchronous messaging and system integration, while improving scalability, release automation, and deployment workflows with Azure DevOps.

Earlier, at Lizard Soft (08/2020–09/2022), I was promoted to Team Lead after 7 months and managed a cross-functional team of 8 people while still contributing directly to the codebase. I migrated a monolith to Azure-based microservices and implemented backend components with ASP.NET Core, Azure Service Bus, Azure Functions, and Azure SQL, and I’ve continued to bring a clean, maintainable architecture mindset—evident in my Clean Architecture work at Agile Fuel (09/2019–08/2020) and my multi-tenant SaaS backend ownership at Applikator (07/2014–09/2019).