Open to opportunities

Денис Саюк

@0004559

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I build production AI features and full-stack products with React, Next.js, NestJS, and TypeScript.

Ukraine

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What I'm looking for

I'm looking to build product-facing applications and production AI features end-to-end, collaborating closely with product and design from data model through UI.

I've shipped MCP- and RAG-based document-processing features at Lumitech that save client teams an estimated 600 hours annually.

I lead development of Next.js applications on NestJS backends across four products, owning features from design through production. I design GraphQL, REST, and real-time WebSocket APIs and maintain four microservices using trunk-based development.

Previously at CGSTeam, I built microservice systems with RabbitMQ across four services handling up to 500 requests per second. I delivered real-time content-management features used daily by around 200 staff, alongside React Native and Next.js/NestJS products.

I enjoy taking product-facing features end-to-end, from data models and service communication through to polished UI. My project work includes tactical mapping, self-hosted time tracking, and a local-services marketplace.

Experience

Work history, roles, and key accomplishments

Current

Full-Stack Developer

Current

Lumitech

Jun 2025 - Present (1 year 2 months)

Led development of Next.js applications on NestJS backends across 4 products, owning features from design to production. Built production AI features on MCP and RAG architectures, saving client teams an estimated 600 hours per year.

Next.js React NestJS TypeScript GraphQL WebSockets PostgreSQL MCP RAG Microservices Trunk Based Development

Full-Stack Developer

CGSTeam

Mar 2024 - Jun 2025 (1 year 3 months)

Built and maintained microservice architectures with RabbitMQ, handling up to 500 requests/sec at peak. Implemented real-time features via WebSockets and REST APIs for an internal content-management platform used by ~200 staff.