Senior Frontend Developer

StellarTech is looking for Senior React Developer to join our team and lead the development of high-performance marketing funnels. In this role, you will architect and build custom UI components from scratch — covering 95% of the UI without relying on third-party component libraries — ensuring our funnels are fast, conversion-optimized, and fully tailored to our brand.

What You’ll Do:

• Custom Component Development: Build and maintain a comprehensive internal component library covering 95%+ of the UI surface. Components are built from scratch without third-party libraries (no MUI, Chakra, Ant Design, etc.), with clean APIs and clear documentation. Collaborate with designers to deliver functional, brand-aligned implementations.
• Marketing Funnel Engineering: Architect and develop multi-step marketing funnels, including landing pages, lead capture flows, upsell sequences, and thank-you pages. Implement dynamic content rendering, conditional logic, and form validation. Integrate with marketing platforms via REST APIs and manage funnel state across steps using appropriate storage strategies.
• Payment Integrations: Integrate payment gateways (Stripe, PayPal, or similar) into funnel flows, including secure form handling, webhook processing, and error recovery.
• Performance Optimization: Own Core Web Vitals across all funnel pages targeting Lighthouse scores of 95+. Apply code splitting, lazy loading, tree shaking, and critical CSS. Use React DevTools Profiler and Chrome Performance panel to identify and eliminate redundant re-renders through memo, useMemo, useCallback, and smart component splitting.

What We’re Looking For:

• 5+ years of professional React development experience
• Proven track record building 90%+ custom UI without component libraries
• Understanding of the Critical Rendering Path
• Deep understanding of React reconciliation, the virtual DOM, and rendering behavior
• Experience with state management solutions (Redux Toolkit, Zustand, Jotai) and knowing when to use global vs local state
• Solid understanding of Local Storage, Session Storage, and cookies — including security implications and appropriate use cases within funnel flows
• Hands-on experience with React DevTools Profiler and techniques to prevent redundant re-renders
• Experience integrating payment gateways (Stripe, PayPal, or similar) in production
• Strong command of HTML5, CSS3, and modern TypeScript

Nice to have:

• Experience with Next.js and server-side rendering
• Familiarity with feature flagging tools
• Familiarity with A/B testing and analytics event tracking
  

Why You'll Love Working With Us:

• Innovative Environment: We're all about trying new things and pushing the envelope in EdTech.
• Freedom: Flexible role based either remotely or hybrid from one of our offices in Cyprus, Poland.
• Health: company-provided medical expense compensation.
• AI solutions: АІ subscription and other tools.
• Balance: Flexible paid time off, you get 21 days of annual leave + 10 bank holidays.
• Collaborative Culture: Work alongside passionate professionals who are as driven as you are.