Oleksandr

Oleksandr Barskyi
Frontend / Full-Stack Engineer
Email: [открыть контакты](см. выше в блоке «контактная информация») | Phone: [открыть контакты](см. выше в блоке «контактная информация») | Ukraine / Remote | Portfolio:
about-me-alpha-henna.vercel.app

Professional Summary
Frontend-focused Full-Stack Engineer with 5+ years of experience building web, mobile, backend and data-oriented products. From
2022 to 2026, collaborated with DreamX / BudgetYid on React Native / Expo and web products for personal finance and related digital
products. Strong practical background with React, Next.js, React Native / Expo, TypeScript, Node.js APIs, Firebase, REST / GraphQL
integrations, Shopify Liquid/theme work and production deployment workflows.

Core Skills
Frontend: React, Next.js, React Native, Expo, TypeScript, JavaScript, HTML5, CSS3, responsive UI, component architecture, forms, dashboards,
charts, modals, bottom sheets, UI states.
Shopify / E-commerce: Liquid themes, Online Store 2.0 concepts, product cards, collections, cart / checkout flows, Shopify Admin API, Storefront
API concepts, webhooks, theme customization, product media, sale pricing.
Backend / API: Node.js, Spring Boot, REST APIs, GraphQL, Firebase Auth / Firestore, PostgreSQL, MySQL, MongoDB, auth token flows, OAuth,
CORS / proxy debugging, webhooks.
Mobile & Builds: React Native / Expo, EAS Build, Android / iOS testing, mobile redirects, camera / capture flows, app troubleshooting.
Cloud / DevOps: Vercel, Firebase, Docker, Docker Compose, GitLab CI/CD, Linux, DigitalOcean, deployment environments.
Additional: Java, Python, C#, C / C++, Unity WebGL, Angular basics, ML / data analysis basics.

Professional Experience
Frontend & Full-Stack Engineer - DreamX / BudgetYid Collaboration
May 2022 - 2026 | Contract / collaboration | Remote
• Collaborated with DreamX company and friends on applications and websites, including BudgetYid / JoyBudget personal-finance product
work.
• Built React Native / Expo and web product features: budgeting screens, categories, transactions, dashboards, Firebase authentication,
notifications and reusable mobile UI components.
• Worked on API integration, auth flows, Plaid-related setup, subscription/admin flows, user-facing billing states and data-heavy product
screens.
• Created and launched the DreamX company website: dreamxweb.com; after launch, maintenance and updates were continued by the
DreamX team.
Independent Frontend & Full-Stack Engineer / Individual Entrepreneur
May 2022 - Present | Remote / Ukraine
• Delivered React / Next.js web apps and React Native / Expo mobile apps for health, analytics, authentication-heavy and business-product
workflows.
• Integrated backend APIs and debugged production issues around token flows, Google / Apple / email auth, CORS / proxy behavior, mobile
redirect login, Vercel domains and backend communication.
• Implemented data-heavy product screens: biomarkers, capture/review flows, charts, forms, modals, bottom sheets, mobile navigation and
responsive web pages.
• Completed Shopify theme/product-card work: Liquid section/snippet structure, responsive Tailwind CSS styling, product media hover states,
sale badge, price rendering and deployment checks.
Selected independent / collaboration projects:
• DreamX / BudgetYid / JoyBudget (May 2022 - 2026) - React Native / Expo and web product work for personal finance: budgets, categories,
transactions, Firebase auth, Plaid-related setup, subscription/admin flows and reusable mobile UI.
• Longevity Leon - React Native / Expo health app: onboarding, profile/home dashboards, capture screens, biomarker review flows, integrations
and Android build/testing workflow.
• OuTreX - React / Next.js and Vercel web product: API token integration, Google redirect/auth debugging, CORS / proxy fixes and production
domain configuration.
• Shopify product-card / theme assessment - Liquid, Tailwind CSS, responsive product UI, secondary image hover, sale badge, price rendering
and theme deployment checks.
• SizeMatch iOS application - Built iOS mobile app published on the App Store: apps.apple.com/ua/app/sizematch/id6443542455.
• RadmirTech / NB Data Logger collaboration - Worked with server-side and embedded / NB-IoT solutions, including NB Data Logger:
radmirtech.com.ua/en/product/nb-data-logger.

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Professional Experience (continued)
System Architect - CNIITU-IT
Sep 2019 - Feb 2022 | Ukraine
• Architected and delivered an electric vehicle charging station system in Ukraine: React web client, Spring Boot backend, OCPP 1.6 embedded
Java application inside a charging station and Android / iOS WebView apps.
• Built the unified virtual exhibition platform: React web client, Unity WebGL 3D online exhibition and Spring Boot backend.
• Set up and maintained a GitLab instance on DigitalOcean; created development, testing and production environments for the programming
team.
• Main stack: Java, JavaScript, SQL, React, Spring Boot, Unity WebGL, Docker, Docker Compose, GitLab.
Software Engineer - RadmirTech
May 2018 - Sep 2019 | Ukraine
• Worked on an analytical platform for gas consumption data: radmirtech.com.ua/en/product/hasgas-direct-cabinet.
• Created embedded firmware for STM32 microcontrollers to send gas meter data to the server.
• Built a Spring Boot backend collecting data into PostgreSQL and exposing HTTP endpoints for frontend applications.
• Main stack: C / C++, Java, SQL, Keil uVision, Spring Boot, PostgreSQL.

Teaching / Mentoring
Teacher - Pre-university Education Center of V. N. Karazin Kharkiv National University
Jan 2017 - Sep 2018 | Kharkiv, Ukraine
• Taught web programming for schoolchildren: HTML, CSS and JavaScript; guided students in creating and publishing their own websites.

Education
• PhD studies, V. N. Karazin Kharkiv National University | 2022 - Present - Formal verification of programs based on Actor Model using
dependent types; Faculty of Mathematics and Computer Science.
• Master Degree, V. N. Karazin Kharkiv National University | 2021 - Theoretical and Applied Computer Science.
• University of L'Aquila | 2021 - Mathematical Engineering.

Languages
Ukrainian - native | English - B2 | Italian - B2 | Russian - C1

Selected Technical Strengths
• End-to-end feature ownership: frontend UI, API integration, authentication, deployment and production troubleshooting.
• Strong debugging mindset across web, mobile and backend boundaries: token flows, CORS / proxy, redirects, mobile builds, app testing and
deployment environments.
• Comfortable in small teams: direct client communication, technical mentoring, architecture decisions and clear handoff documentation.

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