Sergii Severynov

Senior Software Engineer with 8+ years of experience building scalable web applications with React, TypeScript and Next.js. Strong in frontend architecture, team leadership, and delivering clean, maintainable code with a strong frontend focus. Passionate about performance, developer experience, and aligning technology with business outcomes.

• Promoted from Senior Frontend Software Engineer to Team Lead, overseeing a distributed team of 5 developers working on Lano’s global employment and payroll platform.
• Proposed and led a major frontend refactor, improving code structure for shared logic and role-specific views. Successfully completed within a year, boosting maintainability and onboarding speed for new features.
• Initiated and implemented automatic code checks and shared component conventions, enhancing code consistency and reducing duplication across the monorepo.
• Contributed to high-level architecture decisions and frontend/backend API design in a Ruby on Rails + React monorepo environment.
• Expanded scope to backend development (Ruby on Rails) in both customer-facing and internal tools, tackling fullstack tickets and small backend features.
• Improved frontend performance and data handling by adopting TanStack Query and Zod for schema validation.
• Mentored engineers, reviewed pull requests, and drove knowledge sharing to foster a culture of quality and autonomy.

Tech stack:TypeScript, React, Redux, TanStack Query, Material-UI, zod, Ruby on Rails, CI/CD, REST API, Unit Testing.

• Led frontend and cross-functional development of a multi-tenant, multi-language educational platform used by families and children.
• Architected and implemented a modular system with 6 frontend apps and 7 microservices, enabling fast feature rollout and clean separation of concerns.
• Developed reusable interactive components (games, lessons) as npm packages, later integrated into a standalone Next.js-based app.
• Initiated and completed a full accessibility refactor, achieving 100% accessibility compliance in Google audits.
• Delivered advanced product features including live video/chat, real-time collaboration, content moderation tools, and a custom payment flow.
• Built and launched additional startup projects:
  • Cryptocurrency app with Web3 integration (staking, dashboard, admin panel).
  • Telehealth platform with modern UI and full accessibility overhaul.
  • Marketplace MVP with SEO-optimized, SSR-based frontend.
• Contributed to team hiring, mentoring, and onboarding, while also handling feature planning in a startup-style environment.

Tech stack:TypeScript, React, Next.js, Redux, GraphQL, AWS, Docker, CI/CD, WebSockets, Unit Testing, SEO, Web Accessibility.

• Developed several production-grade frontend applications, including a progressive web app for travel planning with real-time updates, offline support, and third-party integrations (e.g., Expedia, Booking).
• Built a cryptocurrency trend analysis platform with SEO-optimized server-side rendering and dynamic data visualizations.
• Designed and implemented a form engine and modular widget system for fintech use cases, enabling custom forms and reusable UI blocks.
• Mentored interns, participated in tech hiring, and contributed to internal knowledge sharing through meetups and code reviews.

Tech stack:TypeScript, React, Next.js, Redux, Firebase, Material-UI, WebSockets, PWA, CI/CD, SEO.

• Delivered frontend solutions for real estate dashboards and small business websites, focusing on UI improvements, responsiveness, and usability.
• Regularly updated legacy codebases and integrated new features across client projects in diverse domains.

Tech stack:JavaScript, React, Redux, Material-UI.

• Negotiation, execution, signing and support of contracts for the sale of aviation goods and services.