Sergey Krizhanovskiy

I am a Senior Frontend Developer with 5+ years of experience building high-load, customer-facing applications and complex user interfaces. I specialize in React, Next.js, Gatsby, TypeScript, and modern application architecture. My work focuses on creating fast, scalable, and maintainable front-end solutions that directly contribute to business growth, user engagement, and SEO performance.
What I do:
Develop modern, responsive, and accessible UI using React, Next.js, Tailwind, and component-driven architecture.
Design and optimize frontend application architecture for scalability, maintainability, and high performance.
Implement SEO-focused dynamic page generation using Gatsby / Next.js and CMS platforms such as Strapi, enabling marketing teams to launch campaigns without developer involvement.
Integrate with REST API and GraphQL backends, ensuring efficient data handling and smooth user interaction.
Optimize Core Web Vitals (LCP, FID, CLS) and improve performance through code-splitting, lazy loading, render optimization, caching, and bundler tuning.
Build custom UI component libraries and reusable design systems that speed up product development.
Work with CI/CD (GitLab), testing frameworks (Jest, Cypress, Playwright), and maintain high code quality standards.

Key Results Delivered:
Built a dynamic SEO page generation engine that enabled non-technical teams to create hundreds of pages autonomously, significantly increasing organic traffic and user acquisition.
Improved Core Web Vitals of a high-traffic telecom product (44M+ users) by ~20%, resulting in faster user experience and better search performance.
Developed an interactive 3D transport data visualization using Three.js, greatly enhancing presentation clarity and user engagement.

Tech Stack:
React, Next.js, Gatsby, TypeScript, JavaScript (ES6+), React Query, Redux, GraphQL, REST API, Strapi, CI/CD, Docker, Tailwind, Styled Components, Jest, Playwright, Cypress, Vite.