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Markiyan User

@markiyanuser

Full-Stack Developer at Insiders who introduced Kafka event-driven messaging and cut a core API endpoint's response time by 2.5 seconds.

Ukraine

Message

At Insiders, I design backend services and PostgreSQL schemas for an e-commerce platform with customer, seller, and admin interfaces. I introduced Kafka to replace synchronous service-to-service calls with event-driven messaging and optimized a core API endpoint, cutting its response time by 2.5 seconds.

I also ship web, iOS, and Android clients, set up CI/CD, and build AI-assisted features with OpenAI API and LangChain, including an ElevenLabs voice integration. Since 2025, I’ve taken part in architecture and system-design decisions, reviewed code, and mentored junior developers.

Experience

Work history, roles, and key accomplishments

Current

Full-Stack Developer (backend focus)

Current

Insiders

Feb 2024 - Present (2 years 9 months)

Designed backend services and PostgreSQL schemas with NestJS, Express, GraphQL and Prisma. Introduced Kafka for event-driven messaging, optimized API response times, and led CI/CD and AI feature development.

NodeJS NestJS Express PostgreSQL Prisma GraphQL Kafka Docker GitHub Actions CI CD OpenAI API Lang Chain ElevenLabs React Next.js React Native

Full-Stack Engineer

Freelance

Aug 2023 - Jan 2024 (5 months)

Delivered web apps for independent clients from requirements to deployment using Node.js/Express, React, Docker, and AWS. Set up CI/CD and handled client communication directly.

NodeJS Express React Docker AWS CI CD Shopify