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. Totaly remore setup. 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.