Олександр

Oleksandr Shtefan
Krakow, Poland · Telegram: @xobandech · [open contact info](look above in the "contact info" section) · LinkedIn · GitHub

SUMMARY
Full-stack engineer with 3+ years of production experience across backend (Go, Node.js/NestJS) and frontend
(React, Next.js). Architected ad-tech platforms processing $50K+/day in ad spend and millions of daily
events, integrating 10+ third-party APIs. Led a 3-engineer team end-to-end — from database schemas and
REST APIs to React/Redux dashboards and Docker deployments.

CORE SKILLS
• Backend: Node.js · NestJS · Hapi · Express · Go · REST API · GraphQL
• Frontend: React · Redux · Next.js · HTML/CSS · Tailwind CSS
• Languages: TypeScript · JavaScript (ES6+) · Go · Python
• Databases: MongoDB · PostgreSQL · Redis · ClickHouse
• Messaging & Testing: RabbitMQ · BullMQ · Jest · React Testing Library
• Infrastructure: Docker · CI/CD · Git · Sentry

EXPERIENCE
MGID — Full-stack Engineer / Team Lead | Jan 2023 – Jan 2026, Krakow
• Architected and built a custom performance marketing platform from scratch — Go backend processing
millions of daily clicks, NestJS API layer, and React/Redux dashboard used by 10+ teams managing
thousands of campaigns
• Integrated 10+ third-party APIs (Outbrain, Taboola, Voluum, System1, Facebook Ads, and others) with
rate limiting, error recovery, and async data normalization via RabbitMQ
• Designed data pipelines and aggregation logic in MongoDB and PostgreSQL, optimizing query
performance with custom indexes, aggregation pipelines, and ClickHouse for analytics
• Led a 3-engineer team: code reviews, architecture decisions, task distribution, mentoring, and direct client
communication with media-buying teams
• Deployed services via Docker with CI/CD pipelines, Jest test coverage, Redis caching, and Sentry error
tracking

Freelance — Full-stack Developer | Jun 2022 – Dec 2022
• Delivered React/Next.js web applications and landing pages for multiple clients, handling frontend UI,
Node.js backend APIs, and WordPress integrations

EDUCATION
B.Sc. Intelligent Systems · Technical University of Košice · 2022 – 2025

CERTIFICATIONS
• Complete React Developer 2023 (Udemy)
• Elements of AI (University of Helsinki)

OTHER
Languages: Ukrainian (Native) · Russian (Native) · English (Intermediate) · Slovak (Intermediate) · Polish (A2)