Frontend Engineer (React)

About the Position

Frontend Engineer (React)

We are seeking a Senior Frontend Engineer (React) to join our team at Shelf in Warsaw, Poland. This role is for senior frontend engineers who can design and own business-critical user experiences for agentic AI products.

Responsibilities

• Design and ship production Next.js SSR applications with complex state, high-load scenarios, and real-time AI interactions at scale
• Build interfaces for AI-powered features: streaming LLM responses, semantic search across millions of documents, interactive knowledge graphs, and agentic builders
• Architect component libraries and maintain the design system, ensuring reusability, accessibility, and consistent UX across the platform
• Deliver enterprise-grade functionality: localization, accessibility compliance, cross-browser support, and security
• Take full ownership after launch: monitor performance in production, optimize bundle sizes, instrument for Core Web Vitals, and ensure things scale gracefully
• Keep the bar high on code quality, testing, and craft through thoughtful code review and mentorship

Requirements

• Over 5 years of frontend engineering experience, including 3+ years specializing in React and modern TypeScript
• Production Next.js experience: SSR applications at scale, app router, server components, and the trade-offs between SSR, SSG, and CSR
• Complex state management for hard scenarios: real-time collaboration, optimistic updates, multi-tenant isolation, large-scale data sync
• Experience building AI/LLM interfaces: streaming token responses, chat UIs, semantic search, or similar real-time AI interactions
• High-load performance work: you monitor Core Web Vitals and know how to improve them under heavy traffic and large datasets
• Enterprise application depth: localization, accessibility, security, and compliance, you understand the complexity beyond "making it work"
• A security-conscious approach to engineering: you handle sensitive data carefully and think about the security implications of what you ship
• Strong craft and product instinct: you don't wait for perfect designs, you spot UX issues and propose solutions, and you're never satisfied with "good enough"
• AI-native working style. You already use AI coding agents daily and are eager to push the boundaries of harness engineering
• Clear communication. You articulate design decisions and technical trade-offs clearly, verbally and in writing

Nice to Have

• 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/Python: you can read backend code and contribute to API design discussions
• Built or contributed to design systems or open-source component libraries

We Offer

• Competitive salary
• Full-time position
• On-site work in Warsaw, Poland
• Opportunity to work in a high-growth, innovative company
• Collaborative and dynamic team environment

About the Company

The enterprise is going agentic and we are creating a unique operating system for an automated future. Most AI agents break the moment they hit real business complexity. That’s why we built a platform that models a company's policies, workflows, and operational logic into an AI Data Model. Shelf enables AI Agents to reliably reason and deliver precise and reliable outcomes at scale.

We already have what most AI startups are still trying to earn: Enterprise customers such as Glovo, Nespresso, and HelloFresh, real production data, and tens of thousands of users. Customers trust us with operational knowledge: Our platform is highly reliable and secure with SOC2, HIPAA-ready security practices, and mature integrations in place.

Location – Warsaw, work from the office.