Frontend React Engineer

About the Role Our client is a fast-growing technology company operating in the enterprise AI and software industry. The company is developing an AI-native platform that helps enterprises model complex business processes, workflows, policies, and operational knowledge, enabling AI agents to deliver reliable and scalable business outcomes. The platform is already used by international enterprise customers and supports real production workloads at scale. We are looking for a Senior Frontend React Engineer to join the team in Warsaw. This is a hands-on role focused on building business-critical user experiences for AI-powered products. You will work with modern frontend technologies, complex application state, real-time AI interactions, and enterprise-grade functionality. You will have significant ownership over frontend architecture, product decisions, performance, and production quality. The role is 100% office-based in Warsaw. What We Offer Long-term opportunity with a fast-growing enterprise AI product 100% office-based work in Warsaw Opportunity to work on production AI products used by enterprise customers Significant ownership over frontend architecture and product experiences Modern React, Next.js, TypeScript and AI-focused technology stack Opportunity to work in an AI-native engineering environment Collaboration with experienced engineers and product teams A role with strong technical ownership and room for professional growth Daily tasks: - Design and develop production-grade Next.js applications using React and TypeScript - Build complex user interfaces for AI-powered features, including streaming LLM responses, chat interfaces, semantic search, knowledge graphs, and agentic workflows - Work with complex application state, real-time interactions, optimistic updates, and large-scale data synchronization - Design and maintain reusable component libraries and contribute to the company's design system - Ensure high standards of accessibility, localization, cross-browser compatibility, security, and enterprise readiness - Optimize frontend performance for high-load environments and large datasets - Monitor and improve Core Web Vitals, bundle sizes, and overall application performance - Make frontend architecture decisions and contribute to API and technical design discussions - Take ownership of features throughout their lifecycle, from initial implementation through production monitoring and optimization - Participate in code reviews and contribute to engineering standards and best practices - Collaborate closely with product and engineering teams to turn complex and ambiguous requirements into intuitive user experiences - Use AI-assisted development tools and coding agents as part of the everyday engineering workflow Requirements 5+ years of professional frontend engineering experience 3+ years of hands-on experience with React and modern TypeScript Strong commercial experience with Next.js and production SSR applications Good understanding of Next.js App Router and Server Components Practical understanding of SSR, SSG, and CSR and the trade-offs between them Experience working with complex state management and real-time application behavior Experience building high-performance applications used under significant traffic or with large datasets Strong understanding of frontend performance optimization and Core Web Vitals Experience building enterprise applications where accessibility, localization, security, and compliance are important Experience working with AI/LLM-powered interfaces, such as streaming responses, chat applications, semantic search, RAG interfaces, or similar real-time AI functionality Security-conscious approach to frontend engineering, particularly when working with sensitive or enterprise data Strong product mindset and ability to identify UX problems and propose practical solutions Ability to work independently and take ownership of complex frontend areas Strong communication skills and ability to explain technical decisions and trade-offs clearly Experience using AI coding assistants or coding agents in day-to-day development Nice to Have Experience with React Flow, Highcharts, or other advanced data visualization libraries Experience with vector search interfaces, RAG applications, or generative UI Knowledge of Node.js and/or Python, with the ability to understand backend code and participate in API design discussions Experience building or contributing to design systems or open-source component libraries Experience working with AI coding agents, orchestration tools, CLIs, logs, traces, or similar AI development workflows Must have: React, AI, Next.js, TypeScript, User interface, Design System, Security, API, SSR Nice to have: Highcharts, Data visualization, UI, Node.js, Python, ROOM