Senior Product (Frontend) Engineer

Led migration of the widget editor from a legacy codebase to a modern React architecture based on feature modules, reusable components, and modular state management. Improved delivery speed, reduced bugs, and decreased bundle size.

Improved Core Web Vitals including LCP, CLS, and INP, raising Lighthouse performance from 67–75 to over 90. Built a design system and rebuilt the product UI based on analytics and user data.

Brought the embeddable end-user widget to WCAG 2.1 AA compliance. Integrated OpenAI GPT and Google Gemini into content workflows, reducing manual processing time by 60%.

Led React and TypeScript frontend development across more than five client engagements, including AI SaaS platforms, warehouse management systems, and data visualization products.

Owned frontend architecture, stakeholder communication, technical decisions, and delivery timelines. Improved a client product's LCP from 10 seconds to under 2 seconds by resolving oversized images, render-blocking scripts, and third-party code issues.

Integrated OpenAI GPT and Google Gemini features into multiple client products to automate manual workflows.

Led React and TypeScript development for a personalized learning discovery platform. Designed search, filtering, and recommendation experiences for the course catalog.

Built the data layer with TanStack Query, including caching, prefetching, and optimistic updates. Improved perceived loading times on data-heavy views by up to 40%.

Managed SPA SEO using prerender.io and improved Core Web Vitals across the platform.

Led React frontend development for a cross-chain decentralized exchange with real-time swap aggregation across more than five blockchain protocols.

Delivered multi-chain portfolio analytics and a fiat on-ramp. Unified UI experiences across three independently deployed platform areas built with React and Blazor.

Developed React and MobX user interfaces for Fuzu, a high-load African career platform serving more than 100,000 monthly active users.

Reduced initial mobile load times by over 30% on 2G and 3G networks across B2B and B2C surfaces through code splitting and SSR caching.

Created interactive Canvas API charts with React Spring animations for career insights and job-market trends.

Introduced Next.js server-side rendering for a medical education platform to improve SEO and content delivery performance. Raised the Lighthouse performance score from 50 to 93–95.

Created interactive medical case studies in React and refactored the platform to meet WCAG 2.1 AA accessibility requirements.

Built performance-critical React interfaces for Google Stadia, a cloud gaming platform streaming games at 4K/60fps with input-latency requirements below 100ms.

Optimized React rendering behavior and applied code splitting to reduce unnecessary re-renders and initial bundle size.

Held earlier frontend engineering roles across product and client organizations, building the foundation for more than 12 years of professional frontend experience.

Full career timeline is available at kryvenkosergiy.github.io/cv/experience.