Frontend Engineer (React)

Shelf is building a unique operating system for AI agents to handle real business complexity. Their platform models company policies, workflows, and logic into an AI Data Model, enabling AI Agents to deliver precise, reliable outcomes at scale. They serve enterprise customers like Glovo, Nespresso, and HelloFresh, and maintain a secure, SOC2 and HIPAA-ready infrastructure. The role is based in Warsaw and requires work from the office.

• Over 5 years of frontend engineering experience including 3+ years specializing in React and modern TypeScript.
• Production experience with Next.js SSR applications at scale including app router, server components, and trade-offs between SSR, SSG, and CSR.
• Experience with complex state management for scenarios like real-time collaboration, multi-tenant isolation, and large-scale data sync.
• Experience building AI/LLM interfaces with streaming token responses, chat UIs, semantic search, or similar real-time AI interactions.
• Knowledge of high-load performance optimization and monitoring of Core Web Vitals.
• Understanding of enterprise application requirements including localization, accessibility, security, and compliance.
• Security-conscious engineering practices handling sensitive data responsibly.
• Strong craft and product instinct with the ability to identify UX issues and propose solutions.
• AI-native working style using AI coding agents daily.
• Clear verbal and written communication skills for articulating design decisions and trade-offs.

Strong Plus:

• Experience with React Flow, Highcharts, or other complex data-visualization libraries.
• Hands-on experience with vector search UIs, RAG interfaces, or generative UI.
• Understanding of Node.js or Python including reading backend code and contributing to API design.
• Experience building or contributing to design systems or open-source component libraries.

Frontend React Engineer:

• Design and own business-critical user experiences for agentic AI products.
• Build production Next.js SSR applications with complex state, real-time AI interactions, and multiple layers of enterprise functionality.
• Solve ambiguous frontend problems by understanding user needs and shaping interaction models.
• Build AI-native interfaces like streaming LLM responses, semantic search, and interactive knowledge graphs.
• Architect component libraries and maintain the design system ensuring reusability, accessibility, and UX consistency.
• Deliver enterprise-grade functionality including localization, accessibility compliance, cross-browser support, and security.
• Take full ownership after launch by monitoring performance, optimizing bundle sizes, and ensuring scalability.
• Maintain high standards on code quality, testing, and mentorship through code reviews.

Work location is onsite in Warsaw, Poland.