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Kushnerov Serhii - React Frontend Developer
LinkedIn | [открыть контакты](см. выше в блоке «контактная информация») | @serhii_kushnerov | [открыть контакты](см. выше в блоке «контактная информация») | Kyiv, Ukraine

Summary __________ ​

Frontend Developer with 3+ years of experience building scalable, performant, and secure web applications in e-commerce and enterprise
property tech. Proven ability to cut page load times by 40%+, reduce API and JS overhead through caching and refactoring, and modernize
legacy systems using React, Next.js, TypeScript, and Redux. Led key architectural overhauls and implemented reusable UI component
libraries adopted company-wide. Boosted development velocity and reliability via Storybook, code review standards, and automated testing
practices. Skilled in secure authentication workflows, accessibility-first design, and Agile collaboration across large cross-functional teams.
English level: Upper-Intermediate (B2), enabling effective collaboration in international environments.

Skills __________ ​
​

• React.js, Next.js, TypeScript, Redux Toolkit, MobX, Zustand, Apollo Client/GraphQL;
• Tanstack/React-query, Tanstack/React-table, Tanstack/React-virtual, Tanstack/React-router, React-hook-form, Formik, Zod, Yup;
• Tailwind, SCSS/SASS, Material UI, Mantine UI, ShadCn, Headless UI, Radix UI, Floating UI, Styled Components, Framer Motion, GSAP;
• Webpack, Vite, Jest, Vitest, React-testing-library, Storybook, Playwright, CI/CD, Docker, Axios, ESLint, Prettier, Docker, Node.js;​
• Git (GitFlow), Jira, Asana, Agile, SCRUM, Kanban, SOLID, OOP, FLUX, FSD, SEO, Compound Components Pattern, Figma;​

Experience (3 years) __________ ​

React Frontend Developer ShipCheaper 1yr 6mos, 03/2024 - Now
Responsibilities:
• Led core frontend development of an e-commerce logistics platform using React, Next.js, and Redux to boost performance and UX.
• Optimized UI with code splitting, memoization, and caching for faster loads and smoother interactions.
• Collaborated with backend, design, QA, and compliance teams to deliver features in an Agile environment.
• Integrated GDPR-compliant APIs for shipment tracking, rate calculation, and payment processing.
• Refactored legacy UI components to improve maintainability, performance, and visual consistency.
• Developed and maintained reusable, scalable, and accessible component libraries to support rapid feature delivery.
Achievements:
• Reduced checkout page load time by 42% through frontend optimization, improving conversion rates and user satisfaction.
• Decreased API latency and frontend data usage by 35% with Redux and selective caching for real-time shipping rate updates.
• Improved JavaScript execution by 36% via TypeScript enforcement, code audits, and optimizing components used on high-traffic screens
like shipment creation.
• Introduced code documentation and structured pull request templates, enhancing onboarding efficiency for new developers.
• Increased customer trust and engagement by integrating transparent cost calculation tools and a seamless multi-carrier comparison
interface.

React Frontend Developer JLL 1yrs 7mos, 08/2021 - 03/2023
Responsibilities:
• Built reusable React components and responsive layouts for consistent UI across devices and global markets.
• Refactored legacy frontend into a modular, scalable React/TypeScript/Redux codebase, improving velocity and reducing tech debt.
• Implemented token-based authentication with role-based access to secure client portfolios and property valuations.
• Delivered core features: dashboards, property filters, map browsing, and reporting tools in a 15+ person Scrum team.
• Integrated REST APIs (Node.js, Express) with PostgreSQL/MongoDB for property data, lease terms, and market analytics.
Achievements:
• Reduced production bug reports by 28% by introducing stricter unit testing standards and automated regression checks.
• Improved application load speed by 34% using code-splitting, lazy loading, and optimized rendering for data-heavy dashboards.
• Boosted developer productivity by ~20% by building a shared UI component library with Storybook, used across regional portals.
• Enhanced platform security and compliance with secure session handling and two-step token validation for high-value user flows.
• Accelerated feature delivery cycles by ~40% through a Storybook-driven workflow that cut QA feedback loops.
• Improved API performance by 24% using intelligent caching and Axios request batching for large property searches and market reports.

Education __________ ​

Software Engineering - Master's degree SumDU Sumy, Ukraine
Mentorship __________​
​

IT-STEP: Mentored and taught Frontend Development at IT-Step, helping aspiring developers build real-world skills and industry best
practices.