RO

Roman Onyshchenko

Available to hire

Senior Frontend Engineer | React, Next.js, TypeScript & React Native I help entrepreneurs, small agencies and product teams build and improve responsive web and mobile interfaces.

About

Senior Frontend Engineer | React, Next.js, TypeScript & React Native

I help entrepreneurs, small agencies and product teams build and improve responsive web and mobile interfaces.

Services:
• Websites, landing pages and reusable UI components
• React/Next.js web apps, MVPs and single-page applications
• Dashboards, admin panels and operational workflows
• Ecommerce storefronts, search, cart and checkout interfaces
• API integration, localization, accessibility and performance improvements
• React Native interfaces and mobile app features

From US$25/hour. Available remotely from Ukraine for 20–25 hours/week through Ukrainian B2B or EOR arrangements. Scope, estimates and delivery schedules are agreed before work begins.

I’m Roman Onyshchenko, a Senior Frontend Engineer with about six years of experience delivering and modernizing enterprise React applications, from SPAs and ecommerce to operational workflows. I focus on frontend architecture, clear client/server state boundaries, and building UI that’s testable, accessible, and performance-conscious using React, Next.js, and TypeScript.

Across my work, I’ve led migrations from PropTypes to TypeScript, evolved test strategies toward React Testing Library, and helped shape product-ready interfaces backed by well-structured data flows. I also build end-to-end portfolio projects—from product decisions and data modeling through CI/CD, deployments, smoke checks, and observability—so releases are safer, faster, and measurable.

Featured project: FOGHORNBAY, a personal ecommerce demo with responsive shopping flows, customer accounts, English/Ukrainian localization and a no-charge checkout simulation.
Demo: Website not available. Sign in: https://www.twine.net/signup
Project showcase: Website not available. Sign in: https://www.twine.net/signup
Portfolio and services: Website not available. Sign in: https://www.twine.net/signup

  • Joined October 2026

Languages

  • UkrainianFluent
  • EnglishAdvanced

Industry experience

  • Software & Internet
  • Financial Services
  • Retail
  • Media & Entertainment

More experts

Projects · 1

FOGHORNBAY — Next.js Ecommerce & Frontend Development

Personal project · Design and development by Roman Onyshchenko Live demo](https://www.twine.net/signin · Source code](https://www.twine.net/signin · Full showcase](https://www.twine.net/signin Overview A responsive Next.js ecommerce demo covering the journey from product discovery to checkout, with customer accounts and a separate AdminJS application. The public demo simulates orders without charging money. Design and shopping flows Dark navy and charcoal surfaces, yellow action accents and prominent product imagery keep the interface consistent. A light theme offers an alternative. Layouts adapt to desktop, tablet and mobile, with English/Ukrainian localization. Category navigation, filters, sorting and live search suggestions Product galleries, variants, pricing, specifications and reviews Cart and wishlist flows, authentication and localized order history Checkout with delivery/payment choices, order summary and coupon support Catalog and filters](https://www.twine.net/signin Product details and variants](https://www.twine.net/signin Checkout](https://www.twine.net/signin Localized order history](https://www.twine.net/signin Responsive interfaces Tablet navigation and mobile filter/search panels adapt the same shopping workflows to smaller screens. Tablet catalog navigation](https://www.twine.net/signin Mobile filters](https://www.twine.net/signin Mobile search](https://www.twine.net/signin Engineering Next.js, React, TypeScript, Chakra UI and next-intl power the storefront. Prisma and PostgreSQL support the shared data model; Better Auth handles account flows. AdminJS supports catalog, order and content management. The project also includes Stripe integration, Resend emails, SEO metadata and Sentry monitoring. Frontend services I help entrepreneurs, small agencies and product teams with React.js, Next.js, TypeScript and React Native projects: Websites, landing pages and reusable UI components Web apps, MVPs, SPAs, dashboards and admin panels Ecommerce storefronts and checkout interfaces API integration, localization, accessibility and performance improvements React Native interfaces and mobile features From US$25/hour · 20–25 hours/week · Remote from Ukraine. Open to Ukrainian B2B or EOR arrangements. Scope, estimates and timelines agreed before work begins. Portfolio and services](https://www.twine.net/signin · Discuss a project](https://www.twine.net/signin

  • Front-End Developer
  • Software Engineer
  • Web Developer

Work experience

Senior Software Engineer · EPAM SystemsAug 2020 – Present · 6 yrs 4 mos

Delivered data-heavy enterprise workflows including complex forms, sortable/filterable tables, charts, and visualization interfaces while protecting client confidentiality. Modernized legacy JavaScript/Java UI, collaborated with design on feasible UX improvements, and created reusable inputs, selects, and tables. Migrated a React component surface from PropTypes to TypeScript and transitioned tests away from Enzyme toward React Testing Library. Built frontend business logic for a finance-oriented workflow product and worked with backend engineers to reduce API calls and provide frontend-ready data structures. Reviewed code, mentored a junior engineer, and contributed onboarding documentation and notes for non-obvious technical decisions.

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