Senior UI Engineer & Full Stack
SaaS, FinTech, E-commerce, EdTech, AI products, CRM / ERP, Healthcare, Travel, Media, Social, Developer tools, Cybersecurity, Marketplace, Logistics
Available for remote B2B contracts globally
Iryna Vynnychenko
Senior UI Engineer & Full Stack Developer
Iryna Vynnychenko, senior UI engineer & full stack developer in Kyiv. React and Next.js for SaaS, MVPs, and Telegram Mini Apps. 8+ years in production, 4,200+ Upwork hours, 100+ launched projects.
Social Links
Hire me for
Sites, web apps, Mini Apps, and AI — shipped as a senior engineer, not an agency handoff.
Website development
Marketing sites on Next.js, WordPress, or Webflow — stack from the job, not from a trend.
Web app development
Product UIs on Next.js and React — dashboards, accounts, booking, checkout.
Telegram Mini App development
Mini Apps, payment bots, booking, shops — Next.js inside Telegram.
AI solutions for business
RAG on your data, agents with a human confirm, CRM hooks — ROI, not a demo chatbot.
About
Senior UI Engineer & Full Stack on React and Next.js: SaaS, MVPs, AI-powered web apps, Telegram Mini Apps.
I ship product UI in React and Next.js — App Router, Server Components, TypeScript. From Figma or a brief to production.
Senior UI Engineer & Full Stack. React and Next.js in production.
What I take on
- 8+ years in production: SaaS, MVPs, Web Apps on React and Next.js
- Senior UI Engineer & Full Stack: React, Next.js, TypeScript, UI/UX to Code, AI features in the product
- Direct contractor. Available for remote B2B contracts globally. Accountable for the result, not a handoff
Stack
AI Integrations & Features
- Vercel AI SDK
- Figma-to-Code via MCP
- Streaming UI (SSE / WebSockets)
- AI-assisted development
- Workflow automation
- AI-powered internal tools
LLM Integrations
- OpenAI & Anthropic APIs
- Prompt engineering
- Structured outputs
- Function / tool calling
- Embeddings
- Vector databases
- Context management
- AI agents
- Multimodal AI
Backend & Databases
- Node.js
- Python
- PHP
- PostgreSQL
- Prisma ORM
- API Integration & Orchestration
Projects(100+)
- Multi-tenant product systems on Next.js + PostgreSQL/Prisma - isolated data, built to grow from dozens to thousands of users
- High-traffic delivery: SSR/SSG/ISR, CDN caching (CloudFront / Vercel Edge / VPS), code splitting, Core Web Vitals under load
- AWS serverless: S3, CloudFront, Amplify - preview vs production isolation, CI/CD, repeatable deploys
- API backends at scale (Node.js, REST/GraphQL) with TanStack Query - cache, retries, and optimistic UI for live products
Selected public work
Client Testimonials
“Iryna turned our Figma design into a live page flawlessly and ahead of schedule.”
Independent contractor since 2018
Frequently Asked Questions
Answers to common questions about working together
What is your typical project workflow?
For a marketing site we start from the brief or Figma. For product work we start from the domain: business rules, data model, existing APIs. Then architecture, milestones, iterative delivery with daily updates, QA, and deploy. You work with me directly - no middle managers.
Do you work under NDA (Non-Disclosure Agreement)?
Yes, absolutely. I value my clients' security and intellectual property. I am fully ready to sign a standard NDA before we discuss any confidential project details or share source code.
Which technologies do you specialize in?
Frontend: Webflow, WordPress, static sites, GSAP / Lottie / Framer Motion. Fullstack: Next.js - Server Components, Server Actions, API Routes, PostgreSQL / Prisma. TypeScript on the whole path.
How do we get started?
We can schedule a video call or chat via Upwork/Telegram/WhatsApp to discuss your project scope. Once we align on requirements, I can provide a fixed-price estimate or start on an hourly basis.
Do you work with Ukrainian companies as a registered private entrepreneur?
Yes, absolutely. I am officially registered as a private entrepreneur (Group 3) in Ukraine, meaning we can sign an official contract for web development services, issue invoices, and sign acceptance acts.
How do you drive value?
Architecture & MVPs, performance, design systems, full-stack debugging, and AI-powered backend engineering.
- Architecture & MVPs: Scoping and launching scalable web products from zero to production.
- Performance: Auditing legacy code, cutting bundle sizes, and maximizing page speed.
- Design Systems: Building reusable, accessible (a11y) UI kits for complex apps.
- Full-Stack Debugging: Tracking down and fixing production issues across frontend & backend.
- AI-Powered Backend & Agentic Engineering (Node, Python, PHP): Applying agentic engineering practices - using Cursor & Claude to handle implementation under clear human guidance and test coverage to deliver secure APIs, backend logic, and automated workflows.
What do you build?
Available for end-to-end development or jumping in at any stage:
- Marketing sites: Webflow, WordPress, static HTML, landings and corporate sites.
- Animation and interaction: GSAP, Lottie, Framer Motion.
- Fullstack Next.js: UI, APIs, PostgreSQL / Prisma in one web app. NDA-ready.
Let's work together
SaaS, MVPs, and product UI on React and Next.js. Scope and timeline on a short call.
i.vynnychenko@gmail.com