Senior Frontend React Developer

🏢 Summary: Frontend Engineer role focused on building production-grade Next.js SSR applications that power enterprise AI interfaces with real-time LLM streaming, complex state management, and high-load performance. The position involves architecting scalable, accessible, and secure UIs integrated with AI systems and large-scale data services. It requires delivering performant, enterprise-ready frontend solutions for mission-critical AI-driven workflows. 🗂️ Requirements: 5+ years frontend engineering experience, 3+ years commercial experience with React, Production experience with Next.js SSR applications, Advanced TypeScript expertise, Experience with complex state management in large-scale applications, Experience building AI/LLM interfaces with real-time streaming, Proven performance optimization for high-load applications, Experience with enterprise features: i18n, accessibility, security compliance, Strong knowledge of modern CSS and responsive design, Experience integrating REST APIs and WebSockets, Experience with observability and frontend monitoring tools, Experience with AI coding assistants 📃 Skills: React, Next.js, TypeScript, JavaScript, SWR, REST, WebSockets, Tailwind, CSS, Storybook, ReactFlow, Highcharts, Playwright, Datadog, Sentry, Elasticsearch, DynamoDB, PostgreSQL, Aurora, SOC2 🏢 Description: As a Frontend Engineer at Shelf, you’ll craft the interfaces that make enterprise AI accessible and trustworthy. While others are building chatbots, we’re solving the harder problem: how do you build UIs that help users confidently navigate AI-powered systems processing millions of documents, while maintaining enterprise-grade reliability? You won’t just build React components — you’ll architect production-ready Next.js applications that handle high-load scenarios with complex states, real-time AI streaming, and multiple layers of enterprise functionality. Every interface decision you make directly impacts how knowledge workers at the biggest companies in the market interact with their most critical information. This is frontend engineering at its most demanding. You’ll tackle challenges like building real-time streaming interfaces for LLM responses, architecting state management for concurrent AI operations across multiple tenants, creating accessible interfaces for complex knowledge graphs with thousands of nodes, and ensuring blazing fast interactions even with petabytes of searchable content. Your components will bridge everything from enterprise authentication systems to cutting-edge AI models, requiring both sophisticated technical skills and sharp product instincts. We obsess over frontend quality because we’re building the trust layer for AI itself. When your interfaces gracefully handle edge cases, provide clear feedback during AI processing, and remain performant under load, you’re not just meeting UX standards — you’re directly enabling users to trust AI-powered answers and make critical business decisions with confidence. You’ll work on production SSR applications serving thousands of enterprise users, implementing localization for global markets, ensuring accessibility compliance, and maintaining security standards that pass SOC 2 audits. Your code will integrate with our Elasticsearch clusters, DynamoDB tables, and Aurora PostgreSQL databases through the largest park of REST APIs, handling real-time websocket updates for AI streaming and collaborative features. We’re a product company that ships fast without compromising on lasting quality. You’ll work alongside proactive, ever-learning engineers who actively use AI coding assistants (OpenAI Codex, Claude Code) to accelerate development. We build custom MCP servers, implement DSPy pipelines for LLM optimization, and experiment with different AI tools for implementation. In our environment, AI isn’t just what we build — it’s how we build. The best engineers we know are drawn to problems that matter. If you’re excited by the challenge of building interfaces that make the AI revolution actually usable and trustworthy for enterprise users, this role offers the rare combination of technical depth, meaningful impact, and the prestige of solving UX patterns that the industry hasn’t figured out yet. Responsibilities Design and implement production-ready Next.js SSR applications with complex state management, handling high-load scenarios and real-time AI interactions at scale Build interfaces for AI-powered features including streaming LLM responses, semantic search across millions of documents, interactive knowledge graphs, intelligent content recommendations, and AI agentic builders Architect component libraries and maintain our design system in Storybook, ensuring reusability, accessibility, and consistent UX patterns across the platform Develop enterprise-grade functionality including multi-language support, accessibility compliance, cross-browser compatibility, and security implementations that meet SOC 2 standards Create comprehensive technical specifications and component API designs that clearly communicate interface decisions, performance trade-offs, and accessibility considerations Build and optimize data-heavy UIs using React Flow for node-based graphs, Highcharts for analytics visualizations, and custom virtualization for handling large datasets Instrument components for performance monitoring, track Core Web Vitals, implement error boundaries, and build automated visual regression tests with Playwright Take full ownership of the features you build, monitoring their performance in production, optimizing bundle sizes, and ensuring they scale gracefully as user load grows Work with SWR for intelligent data fetching, caching, and revalidation strategies that minimize API calls while keeping UIs responsive and data fresh Integrate with backend services via REST APIs, handle websocket connections for real-time updates, and implement optimistic UI patterns for seamless user experiences Leverage AI coding assistants to accelerate development while maintaining high code quality, and contribute to building internal AI agents that automate frontend workflows Stay current with React ecosystem best practices, Next.js updates, AI UX patterns, and modern frontend architecture—experiment with new approaches and share findings with the team Contribute to our engineering standards and practices through thoughtful code reviews, mentor colleagues on frontend best practices, and actively participate in our culture of continuous learning Requirements Over 5 years of professional frontend engineering experience, including more than 3 years specializing in React and modern JavaScript/TypeScript Production Next.js experience — you’ve built and shipped SSR applications at scale, understand app router patterns, server components, and the trade-offs between SSR, SSG, and CSR Deep TypeScript expertise — you write type-safe code with generics, utility types, and advanced patterns. Complex state management — hands-on experience architecting state solutions for challenging scenarios: real-time collaboration, optimistic updates, multi-tenant data isolation, and large-scale data synchronization Enterprise application development — you’ve built applications with localization (i18n), accessibility, security best practices, and compliance requirements. You understand the complexity beyond “making it work” AI/LLM interface experience — you’ve built interfaces for AI-powered features: streaming token responses, chat UIs, semantic search, or similar real-time AI interactions High-load optimization — proven track record optimizing applications for performance under heavy traffic, large datasets, and concurrent operations. You monitor Core Web Vitals and know how to improve them Modern CSS mastery — strong expertise with Tailwind CSS and/or CSS-in-JS solutions. You can implement pixel-perfect designs while maintaining responsive layouts and dark mode support Write well-structured, testable code with thoughtful component abstractions and clean APIs. You know when to abstract and when to keep it simple Strong problem-solving skills and genuine curiosity — you don’t wait for designs to be perfect but proactively identify UX issues and propose solutions. You’re never satisfied with “good enough” and constantly refine your craft Experience with AI coding assistants (OpenAI Codex, Claude, etc.) and eagerness to push the boundaries of AI-assisted development. Part of this role involves creating AI agents to automate portions of the frontend workflow Familiarity with observability and monitoring tools like Datadog, Sentry, or similar platforms for tracking frontend performance and errors in production Upper-Intermediate or better English skills for technical communication, documentation, and collaborating with distributed teams Present your work effectively both verbally and visually — you can articulate design decisions, create component documentation, and explain technical trade-offs clearly Be a Plus: Experience with React Flow, Highcharts, or other complex data visualization libraries Understanding of Node.js/Python/backend fundamentals — you can read backend code and contribute to API design discussions Experience with SWR, React Query, or similar data fetching libraries Hands-on experience with vector search UIs, RAG interfaces, or semantic search implementations Familiarity with MCP (Model Context Protocol), DSPy, or other cutting-edge AI frameworks Experience with monorepo tools (Lerna, Turborepo, Nx) and managing shared component libraries AWS services knowledge (S3, CloudFront, Lambda) and understanding of serverless architectures Built or contributed to design systems or open-source component libraries Experience with Playwright, Puppeteer, or Cypress for comprehensive E2E testing Experience building AI agent interfaces or agentic AI workflows What Shelf Offers: B2B contract Company Stock Options Hardware: MacBook Pro Modern technical stack. Develop open-source software Premier AI development environment: GitHub Copilot, Claude Code, OpenAI Codex, TypingMind, v0, MCP Servers, plus credits for experimenting with emerging AI tools Why Shelf GenAI will be at least a $18 Trillion market by 2032 and Shelf is a core infrastructure that enables GenAI to be deployed at scale We are blazing the path for the future of Artificial Intelligence globally. Our Leadership Team has deep AI domain expertise and enterprise SaaS background to execute this plan We love our customers and our customers love us. Ask a Shelf customer why, and they’ll tell you it’s because of our innovative capabilities, rock-solid reliability, they truly enjoy working with our people, but most of all — it’s the improvements they see in their business KPIs. We have raised over $60 million in funding and our investors include; Insight Partners, Tiger Global, Base10, and others We have high velocity growth powered by the most innovative product in our category We now have over 100 employees in multiple U.S. states and European countries, and we have ambitious hiring goals over the next few quarters.

🏢 Summary: Senior Frontend React Developer role focused on building enterprise-grade AI-native Next.js applications with complex state, real-time AI interactions, and scalable frontend architecture. The position involves owning frontend systems end-to-end, including UI design, performance optimization, accessibility, and production reliability. Engineers work closely with AI-driven products and modern tooling in a high-ownership environment. 🗂️ Requirements: 5+ years frontend engineering experience, 3+ years React experience, Modern TypeScript expertise, Production Next.js SSR experience, Knowledge of SSR, SSG, and CSR trade-offs, Complex state management experience, Experience building AI/LLM interfaces, Performance optimization and Core Web Vitals knowledge, Enterprise application development experience, Accessibility and localization knowledge, Security-conscious engineering approach, Daily use of AI coding agents, Clear technical communication skills 📃 Skills: React, TypeScript, Next.js, SSR, SSG, CSR, JavaScript, LLM, AI, CoreWebVitals, Accessibility, Localization, Security, ReactFlow, Highcharts, Node.js, Python, RAG, Codex, Claude, Copilot, GitHub 🏢 Description: About Shelf 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. Senior Frontend React Developer: This role is for a senior frontend engineer who can design and own business-critical user experiences for agentic AI products. We want someone who is strong technically, has strong UI judgment, communicates clearly, and has the taste to make complex product experiences simpler, faster, more trustworthy, and easier to evolve over time. Expect real ownership from frontend architecture through production quality. You will build production Next.js applications with complex state, real-time AI interactions, and multiple layers of enterprise functionality. The team is small enough for engineers to make real decisions. Career growth comes from ownership. Titles matter less than the scope you can carry. The people who grow fastest take responsibility for larger product surfaces, drive customer outcomes, and strive to develop better engineering practices. You solve ambiguous frontend problems by understanding the user need, shaping the right interaction model, then shipping, iterating, and keeping the experience healthy in production. We build AI-native. Engineers use Codex, Claude Code, and agents they build themselves. We invest in harness engineering through skills, CLIs, logs, traces, and orchestration. This is a role for someone in a high-growth chapter of their career, who wants to do the best work of their life, learn fast, and win as part of a team going all-in on a hard mission. What You Will Own 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 What Strong Performance Looks Like You turn vague product problems into shipped, well-reasoned interfaces that users trust Complex AI behavior feels legible and controllable to users because of how you built the UI Your components are reusable, accessible, and fast under real enterprise load You bring momentum. Work moves because you are on it What We Are Looking For 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 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/Python: you can read backend code and contribute to API design discussions Built or contributed to design systems or open-source component libraries How We Evaluate Fit We care more about craft, ownership, and the ability to make complex AI feel trustworthy than a perfect match to every library on paper. If you are the kind of engineer who can take a messy, complex enterprise problem and turn it into an interface people trust, we want to talk. What Shelf Offers: B2B contract Company Stock Options Hardware: MacBook Pro Modern technical stack. Develop open-source software A strong AI-native engineering environment with modern tools and room to experiment, including Claude Code, OpenAI Codex, and GitHub Copilot Why Shelf Becoming one of the defining companies of the AI age is a hard plan, and our leadership team has the rare mix of deep AI, knowledge-management, and enterprise SaaS experience to actually execute it We have raised over $60 million in funding; our investors include Tiger Global, Insight Partners, Base10, and others Recognized by Gartner as a Cool Vendor, with high-velocity growth powered by the most innovative product in our category We love our customers and our customers love us. Ask a Shelf customer why, and they'll tell you it's our innovative capabilities and rock-solid reliability, that they enjoy working with our people, and most of all, the improvements they see in their business KPIs We're building fast across three hubs: our New York HQ and our Product and Engineering centers in Warsaw and Lviv

🏢 Summary: Senior full-stack product engineering role focused on building and owning AI-native web product experiences across frontend and backend systems. The position involves end-to-end ownership of product features, collaboration with product and design teams, and improving performance, usability, and reliability in production. The role offers work with modern AI engineering tools and a high-growth environment in Warsaw. 🗂️ Requirements: Senior-level experience shipping production web products, Strong frontend skills with React, Strong frontend skills with TypeScript, Ability to design and ship APIs, Experience with backend logic and data flows, Strong product sense, Understanding of technical trade-offs and scope management, Security-conscious engineering approach, Clear communication across engineering, product, and design, Daily use of AI tools in engineering workflows, Ability to work from the Warsaw office 📃 Skills: React, TypeScript, Python, Node.js, APIs, AI, Codex, Claude, GitHub, Copilot 🏢 Description: About Shelf 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. Job Description This role is for a senior full-stack product engineer who can design and own business-critical product experiences end-to-end. We want someone who is strong technically, has sharp product judgment, communicates clearly, and has the taste to make user experiences and systems simpler, safer, and easier to evolve over time. Expect real ownership from problem discovery through frontend, backend, release, and production quality. The team is small enough for engineers to make real decisions. Career growth comes from ownership. Titles matter less than the scope you can carry. The people who grow fastest take responsibility for larger product areas, drive customer outcomes, and strive to develop better engineering practices. You solve ambiguous product problems by understanding the customer need, shaping the right technical and UX approach, then shipping, iterating, and keeping it healthy in production. We build AI-native. Engineers use Codex, Claude Code, and agents they build themselves. We invest in harness engineering through skills, CLIs, logs, traces, and orchestration. This is a role for someone in a high-growth chapter of their career, who wants to do the best work of their life, learn fast, and win as part of a team going all-in on a hard mission. Location – Warsaw, work from the office. What You Will Own Build and ship user-facing product features across frontend and backend boundaries Turn rough product goals into practical solutions with good scope, sensible trade-offs, and strong execution Work comfortably in UI, application logic, APIs, and data flows rather than stopping at team boundaries Partner closely with product and design while still being able to move when the spec is incomplete Improve usability, clarity, performance, and reliability, not just feature completeness Instrument what you ship so we can learn from production behavior and iterate quickly Use AI tools daily to move faster and help improve internal workflows, tooling, and engineering leverage Keep the bar high on code quality, testing, and ownership after launch What Strong Performance Looks Like You can take a vague product problem and turn it into a shipped, well-reasoned solution Your features feel coherent end-to-end because you care about both implementation and product quality You do not treat frontend and backend as separate worlds; you use both to solve the actual problem You bring momentum. Work moves because you are on it What We Are Looking For Strong senior-level experience shipping production web products Strong frontend ability with React and TypeScript or an equivalent modern web stack Real backend ability. You do not need to be backend-only, but you can design and ship APIs, backend logic, and data flows when the product needs it Strong product sense. You notice awkward flows, weak defaults, and unnecessary complexity, and you improve them Good judgment about scope, iteration, and technical trade-offs A security-conscious approach to engineering: you handle sensitive data carefully and think about the security implications of what you ship Clear communication and comfort working across engineering, product, and design AI-native working style. You already use AI tools as part of daily implementation and problem solving, and you are excited to improve how engineering work gets done Strong Plus Experience with AI-powered product experiences such as chat, search, recommendations, workflows, or agent-like systems Experience with Python, Node.js, or both on the backend Experience owning product areas with limited oversight Strong feel for performance, accessibility, and production quality in complex web applications How We Evaluate Fit We care more about end-to-end ownership, product sense, and the ability to ship meaningful work than a perfect match to every framework on paper. If you are the kind of engineer who can make a product better from multiple angles, we want to talk. What Shelf Offers B2B contract. Company Stock Options. Hardware: MacBook Pro. Modern technical stack . Develop open-source software . GitHub Copilot subscription. A strong AI-native engineering environment with modern tools and room to experiment, including Claude Code, OpenAI Codex, and GitHub Copilot. Why Shelf Becoming one of the defining companies of the AI age is a hard plan, and our leadership team has the rare mix of deep AI, knowledge-management, and enterprise SaaS experience to actually execute it We have raised over $60 million in funding; our investors include Tiger Global, Insight Partners, Base10, and others Recognized by Gartner as a Cool Vendor, with high-velocity growth powered by the most innovative product in our category We love our customers and our customers love us. Ask a Shelf customer why, and they'll tell you it's our innovative capabilities and rock-solid reliability, that they enjoy working with our people, and most of all, the improvements they see in their business KPIs We're building fast across three hubs: our New York HQ and our Product and Engineering centers in Warsaw and Lviv

🏢 Summary: Senior Full Stack Engineer role with end-to-end ownership of user-facing product features across frontend and backend. The position focuses on turning vague product goals into shipped, production-ready solutions with strong product judgment, code quality, and performance. You will work across UI, APIs, and data flows while leveraging AI tools to accelerate development and improve engineering workflows. 🗂️ Requirements: Senior-level experience shipping production web applications, Strong frontend expertise with React and TypeScript or modern equivalent, Ability to design and implement APIs and backend logic, Experience building and maintaining data flows in production systems, Experience instrumenting applications for production monitoring, Ability to write and maintain automated tests, Experience using AI tools in daily development workflow, Strong understanding of performance and reliability in web applications 📃 Skills: React, TypeScript, JavaScript, Python, Node.js, APIs, REST, HTML, CSS, Testing, AI, Git 🏢 Description: About Shelf Shelf builds software that helps enterprises make AI work in the real world. We build products people depend on, which means product judgment, engineering quality, and execution speed all matter at the same time. About the Role This role is for a senior full stack engineer with strong product instincts. You will own meaningful product slices end to end: understand the problem, shape the approach, build the frontend and backend pieces, ship them, and improve them based on real usage. We want someone who is equally comfortable improving a user flow, shaping an API, and closing the loop on quality in production. This is a product engineering role with real end-to-end ownership. Location – Warsaw, work from the office What You Will Own Build and ship user-facing product features across frontend and backend boundaries. Turn rough product goals into practical solutions with good scope, sensible trade-offs, and strong execution. Work comfortably in UI, application logic, APIs, and data flows rather than stopping at team boundaries. Partner closely with product and design while still being able to move when the spec is incomplete. Improve usability, clarity, performance, and reliability, not just feature completeness. Instrument what you ship so we can learn from production behavior and iterate quickly. Use AI tools daily to move faster and help improve internal workflows, tooling, and engineering leverage. Keep the bar high on code quality, testing, and ownership after launch. What Strong Performance Looks Like You can take a vague product problem and turn it into a shipped, well-reasoned solution. Your features feel coherent end-to-end because you care about both implementation and product quality. You do not treat frontend and backend as separate worlds; you use both to solve the actual problem. You bring momentum. Work moves because you are on it. What We Are Looking For Strong senior-level experience shipping production web products. Strong frontend ability with React and TypeScript or an equivalent modern web stack. Real backend ability. You do not need to be backend-only, but you can design and ship APIs, backend logic, and data flows when the product needs it. Strong product sense. You notice awkward flows, weak defaults, and unnecessary complexity, and you improve them. Good judgment about scope, iteration, and technical trade-offs. Clear communication and comfort working across engineering, product, and design. AI-native working style. You already use AI tools as part of daily implementation and problem solving, and you are excited to improve how engineering work gets done. Strong Plus Experience with AI-powered product experiences such as chat, search, recommendations, workflows, or agent-like systems. Experience with Python, Node.js, or both on the backend. Experience owning product areas with limited oversight. Strong feel for performance, accessibility, and production quality in complex web applications. How We Evaluate Fit We care more about end-to-end ownership, product sense, and the ability to ship meaningful work than a perfect match to every framework on paper. If you are the kind of engineer who can make a product better from multiple angles, we want to talk. What Shelf Offers B2B contract. Stock options. MacBook Pro. A strong AI-native engineering environment with modern tools and room to experiment.

🏢 Summary: Senior Backend Engineer role focused on owning and designing production-grade backend systems, from ambiguous problem definition through architecture, implementation, and long-term reliability. The position emphasizes strong system design, distributed systems judgment, and hands-on cloud engineering, with full ownership of services in production. This is a product engineering role with end-to-end responsibility across backend architecture, scalability, and operational excellence. 🗂️ Requirements: Senior-level backend engineering experience in production systems, Strong Python proficiency, Experience designing and operating distributed systems, Knowledge of concurrency, failure handling, and data consistency, Hands-on cloud experience (AWS, Azure or similar), Experience with SQL and NoSQL databases, Ability to design data models and perform schema design, Experience with performance tuning and scalability, Ability to design, implement, and operate backend services end-to-end, Experience using AI tools in daily engineering workflow 📃 Skills: Python, AWS, Azure, SQL, NoSQL, Concurrency, DistributedSystems, Async, APIs, Microservices, LLM, TypeScript 🏢 Description: About Shelf Shelf builds software that helps enterprises make AI work in the real world. We care about the hard part: reliable systems, clear operational logic, and production-grade engineering that makes AI useful instead of brittle. Job Description: This role is for a senior backend engineer who can own important systems, not just implement tickets. You will take ambiguous problems, design the right backend approach, ship it, and keep it healthy in production. We want someone who is strong technically, communicates clearly, and has the judgment to make systems simpler, safer, and easier to evolve over time. This is a product engineering role with real ownership from system design through production. Location – Warsaw, work from the office What You Will Own Design and ship backend services, APIs, data flows, and background processing for production systems. Turn vague requirements into concrete technical plans, trade-offs, and execution. Own services after launch: reliability, observability, performance, and incident follow-through. Make sound decisions around system boundaries, data models, interfaces, and scaling paths. Write clear technical specs, architecture notes, and diagrams when they help the team move faster. Work closely with product, frontend, and platform engineers to deliver end-to-end outcomes. Improve engineering leverage with AI tooling, automation, and internal workflows rather than using AI as a gimmick. Raise the quality bar through code review, design review, and pragmatic technical leadership. What Strong Performance Looks Like You reliably move important backend work forward without waiting to be tightly managed. Your systems are easier to operate and easier to change because of your design decisions. You communicate trade-offs clearly and make the team around you more effective. You use AI tools well: to accelerate analysis, implementation, debugging, writing, and repetitive work, while keeping a high verification bar. What We Are Looking For Strong senior-level backend engineering experience in production systems. Strong Python skills and the ability to design clean, maintainable backend code. Good distributed systems judgment: concurrency, failure handling, data consistency, async work, and service boundaries. Hands-on cloud experience in AWS, Azure, or a similar environment. Comfort with SQL and NoSQL systems, schema design, and performance tuning. Ability to go from problem statement to design to production rollout with real ownership. Clear written and verbal communication. You can explain systems, trade-offs, and incidents without hiding behind jargon. AI-native working style. You already use AI tools in your daily engineering workflow and want to keep pushing that further. Strong Plus Experience with LLM-backed systems, search, retrieval, AI infrastructure, or data-heavy pipelines. Working knowledge of TypeScript or the ability to contribute across the stack when needed. Experience shaping technical direction for other engineers, even without formal management responsibility. How We Evaluate Fit We care more about ownership, systems judgment, and learning velocity than a perfect keyword match to our stack. If you are the kind of engineer who can take a messy problem and turn it into a strong production system, we want to talk. What Shelf Offers: B2B contract. Company Stock Options. Hardware: MacBook Pro. Modern technical stack . Develop open-source software . GitHub Copilot subscription. Access to Claude Code, OpenAI Codex, TypingMind, and MCP Servers. Why Shelf: Our Leadership Team has deep knowledge management and AI domain expertise and enterprise SaaS background to execute this plan We love our customers and our customers love us. Ask a Shelf customer why, and they’ll tell you it’s because of our innovative capabilities, rock-solid reliability, they truly enjoy working with our people, but most of all – it’s the improvements they see in their business KPIs. We have raised over $60 million in funding and our investors include Tiger Global, Insight Partners, Connecticut Innovations, and others We have high velocity growth powered by the most innovative product in our category, 3X growth for 3 years in a row We now have over 100 employees in multiple U.S. states and European countries, and we have ambitious hiring goals over the next few months

🏢 Summary: Senior Backend Engineer role focused on designing, shipping, and owning production-grade backend systems for enterprise AI software. The position requires turning ambiguous problems into scalable architectures and maintaining reliability, performance, and observability in production. It is a product engineering role with full ownership from system design to rollout. 🗂️ Requirements: Senior-level backend engineering experience in production systems, Strong Python proficiency, Experience designing distributed systems, Knowledge of concurrency and async processing, Experience with failure handling and data consistency, Hands-on cloud experience (AWS or Azure), Experience with SQL and NoSQL databases, Ability to design data models and system boundaries, Experience building and maintaining APIs and backend services, Production experience with observability and performance tuning, Ability to write technical specifications and architecture documentation, Experience using AI tools in engineering workflows 📃 Skills: Python, AWS, Azure, SQL, NoSQL, APIs, DistributedSystems, Concurrency, Async, Observability, LLM, TypeScript 🏢 Description: About Shelf Shelf builds software that helps enterprises make AI work in the real world. We care about the hard part: reliable systems, clear operational logic, and production-grade engineering that makes AI useful instead of brittle. Job Description: This role is for a senior backend engineer who can own important systems, not just implement tickets. You will take ambiguous problems, design the right backend approach, ship it, and keep it healthy in production. We want someone who is strong technically, communicates clearly, and has the judgment to make systems simpler, safer, and easier to evolve over time. This is a product engineering role with real ownership from system design through production. Location – Warsaw, work from the office What You Will Own Design and ship backend services, APIs, data flows, and background processing for production systems. Turn vague requirements into concrete technical plans, trade-offs, and execution. Own services after launch: reliability, observability, performance, and incident follow-through. Make sound decisions around system boundaries, data models, interfaces, and scaling paths. Write clear technical specs, architecture notes, and diagrams when they help the team move faster. Work closely with product, frontend, and platform engineers to deliver end-to-end outcomes. Improve engineering leverage with AI tooling, automation, and internal workflows rather than using AI as a gimmick. Raise the quality bar through code review, design review, and pragmatic technical leadership. What Strong Performance Looks Like You reliably move important backend work forward without waiting to be tightly managed. Your systems are easier to operate and easier to change because of your design decisions. You communicate trade-offs clearly and make the team around you more effective. You use AI tools well: to accelerate analysis, implementation, debugging, writing, and repetitive work, while keeping a high verification bar. What We Are Looking For Strong senior-level backend engineering experience in production systems. Strong Python skills and the ability to design clean, maintainable backend code. Good distributed systems judgment: concurrency, failure handling, data consistency, async work, and service boundaries. Hands-on cloud experience in AWS, Azure, or a similar environment. Comfort with SQL and NoSQL systems, schema design, and performance tuning. Ability to go from problem statement to design to production rollout with real ownership. Clear written and verbal communication. You can explain systems, trade-offs, and incidents without hiding behind jargon. AI-native working style. You already use AI tools in your daily engineering workflow and want to keep pushing that further. Strong Plus Experience with LLM-backed systems, search, retrieval, AI infrastructure, or data-heavy pipelines. Working knowledge of TypeScript or the ability to contribute across the stack when needed. Experience shaping technical direction for other engineers, even without formal management responsibility. How We Evaluate Fit We care more about ownership, systems judgment, and learning velocity than a perfect keyword match to our stack. If you are the kind of engineer who can take a messy problem and turn it into a strong production system, we want to talk. What Shelf Offers: B2B contract. Company Stock Options. Hardware: MacBook Pro. Modern technical stack . Develop open-source software . GitHub Copilot subscription. Access to Claude Code, OpenAI Codex, TypingMind, and MCP Servers. Why Shelf: Our Leadership Team has deep knowledge management and AI domain expertise and enterprise SaaS background to execute this plan We love our customers and our customers love us. Ask a Shelf customer why, and they’ll tell you it’s because of our innovative capabilities, rock-solid reliability, they truly enjoy working with our people, but most of all – it’s the improvements they see in their business KPIs. We have raised over $60 million in funding and our investors include Tiger Global, Insight Partners, Connecticut Innovations, and others We have high velocity growth powered by the most innovative product in our category, 3X growth for 3 years in a row We now have over 100 employees in multiple U.S. states and European countries, and we have ambitious hiring goals over the next few months

🏢 Summary: Senior Backend Engineer role focused on designing and owning production-grade backend systems for AI-native enterprise platforms. The position involves building scalable APIs, data flows, and distributed systems with strong ownership from architecture to production operations. Engineers work with AI tooling and cloud infrastructure to deliver reliable, secure, and maintainable systems in a high-growth environment. 🗂️ Requirements: Senior-level backend engineering experience, Strong Python skills, Experience designing production backend systems, Knowledge of distributed systems, Experience with concurrency and async processing, Hands-on cloud infrastructure experience, Database schema design expertise, Performance tuning for high-throughput systems, Security-conscious engineering approach, Ability to own systems from design to production, Clear written and verbal communication, Experience using AI tools in engineering workflows, Ability to work from Warsaw office 📃 Skills: Python, AWS, GCP, Azure, TypeScript, Codex, Claude, Copilot, APIs, LLM 🏢 Description: About Shelf 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. Job Description: This role is for a senior backend engineer who can design and own business-critical systems. We want someone who is strong technically, communicates clearly, and has the judgment to make systems simpler, safer, and easier to evolve over time. Expect real ownership from system design through production. The team is small enough for engineers to make real decisions. Career growth comes from ownership. Titles matter less than the scope you can carry. The people who grow fastest take responsibility for larger systems, drive customer outcomes, and strive to develop better engineering practices. You solve ambiguous problems by shaping the right architectural approach, then ship, iterate, and keep it healthy in production. We build AI-native. Engineers use Codex, Claude Code, and agents they build themselves. We invest in harness engineering through skills, CLIs, logs, traces, and orchestration. This is a role for someone in a high-growth chapter of their career, who wants to do the best work of their life, learn fast, and win as part of a team going all-in on a hard mission. Location – Warsaw, work from the office. What You Will Own Design and ship backend services, APIs, data flows, and background processing for production systems Turn vague requirements into concrete technical plans, trade-offs, and execution Own services after launch: reliability, observability, performance, and incident follow-through Instrument what you ship and use production signal to iterate, not just to keep the lights on Make sound decisions around system boundaries, data models, interfaces, and scaling paths Work closely with product, frontend, and platform engineers to deliver end-to-end outcomes Improve engineering leverage with AI tooling, automation, and internal workflows rather than using AI as a gimmick Raise the quality bar through code review, design review, and pragmatic technical leadership What Strong Performance Looks Like You reliably move important backend work forward without waiting to be tightly managed. Your systems are easier to operate and easier to change because of your design decisions. You make smart trade-offs to unblock shipping - and you stand by those decisions. You keep raising the bar on engineering excellence for yourself and everyone else. What We Are Looking For Strong senior-level backend engineering experience in production systems Strong Python skills and the ability to design clean, maintainable backend code Good distributed systems judgment: concurrency, failure handling, data consistency, async work, and service boundaries Hands-on experience with cloud infrastructure such as AWS, GCP, or Azure Comfort with database schema design and performance tuning for real-time and high throughput scenarios A security-conscious approach to engineering: you build for enterprise-grade requirements, handle sensitive data carefully, and think about the security implications of the systems and AI workflows you ship Ability to go from problem statement to design to production rollout with real ownership Clear written and verbal communication. You can explain systems, trade-offs, and incidents without hiding behind jargon AI-native working style. You already use AI tools in your daily engineering workflow, and you're excited to improve how the team builds, not just your own output: better tooling, workflows, and engineering leverage Strong Plus Experience building agentic systems: AI agents, tool-calling, orchestration, retrieval, or LLM-backed infrastructure in production Working knowledge of TypeScript or the ability to contribute across the stack when needed Experience shaping technical direction for other engineers, even without formal management responsibility How We Evaluate Fit We care more about ownership, systems judgment, and learning velocity than a perfect keyword match to our stack. If you are the kind of engineer who can take a messy problem and turn it into a strong production system, we want to talk. What Shelf Offers: B2B contract. Company Stock Options. Hardware: MacBook Pro. Modern technical stack . Develop open-source software . GitHub Copilot subscription. A strong AI-native engineering environment with modern tools and room to experiment, including Claude Code, OpenAI Codex, and GitHub Copilot. Why Shelf: Becoming one of the defining companies of the AI age is a hard plan, and our leadership team has the rare mix of deep AI, knowledge-management, and enterprise SaaS experience to actually execute it We have raised over $60 million in funding; our investors include Tiger Global, Insight Partners, Base10, and others Recognized by Gartner as a Cool Vendor, with high-velocity growth powered by the most innovative product in our category We love our customers and our customers love us. Ask a Shelf customer why, and they'll tell you it's our innovative capabilities and rock-solid reliability, that they enjoy working with our people, and most of all, the improvements they see in their business KPIs We're building fast across three hubs: our New York HQ and our Product and Engineering centers in Warsaw and Lviv

🏢 Summary: Senior Frontend React Developer role focused on building scalable Next.js applications that power enterprise AI interfaces, including chat, semantic search, and knowledge graph features. The position involves developing high-performance, real-time, and data-intensive user interfaces with strong emphasis on accessibility, security, and code quality. You will contribute to reusable design systems, performance optimization, and AI-assisted development in a modern tech stack. 🗂️ Requirements: 5+ years frontend development experience, 3+ years experience with React, Strong knowledge of JavaScript, Strong knowledge of TypeScript, Strong knowledge of Next.js including SSR, App Router, Server Components, Advanced TypeScript skills, Experience with modern CSS solutions (Tailwind CSS or CSS-in-JS), Experience with complex state management, Experience with real-time collaboration features, Experience building AI-related interfaces (chat, streaming, semantic search), Understanding of localization, Understanding of accessibility standards, Understanding of security standards, Experience with AI coding tools (OpenAI Codex or Claude), Upper-Intermediate (B2) English or higher 📃 Skills: React, Next.js, JavaScript, TypeScript, SSR, Tailwind, CSS-in-JS, SWR, WebSockets, ReactFlow, Highcharts, Storybook, Playwright, Node.js, Python, AWS, S3, CloudFront, Lambda, OpenAI, Claude, Codex, Copilot, Puppeteer, Cypress, Lerna, Turborepo, Nx, MCP, DSPy 🏢 Description: About Us Many companies want to use AI agents, but these tools often have problems with real business tasks. We create a platform that helps AI understand company rules, workflows, and processes, so it can give correct and reliable answers. Our technology is trusted by large international companies and works with leading AI and cloud platforms. Our goal is to help people find better answers and make better decisions with AI. Senior Frontend React Developer As a Frontend React Developer, you will build modern user interfaces that make enterprise AI easy to use and reliable. You will create Next.js applications that work with large amounts of data, real-time AI responses, and advanced business features. Your work will help thousands of users access important information quickly and confidently. What You Will Do Design and develop scalable Next.js SSR applications. Build interfaces for AI chat, semantic search, knowledge graphs, and AI builders. Create data visualizations using libraries such as React Flow and Highcharts. Develop multilingual, accessible, secure, and cross-browser compatible applications. Work with SWR for data fetching, caching, and real-time websocket updates. Build and maintain reusable UI components and a Storybook design system. Improve application performance, monitor Core Web Vitals, and write automated tests with Playwright. Use AI coding assistants to speed up development while keeping high code quality. Participate in code reviews, share knowledge, and support continuous learning within the team. Requirements At least 5 years of frontend development experience. More than 3 years of experience with React and JavaScript/TypeScript. Strong knowledge of Next.js, including SSR, App Router, and Server Components. Advanced TypeScript skills and experience with modern CSS solutions such as Tailwind CSS or CSS-in-JS. Experience building applications with complex state management, real-time collaboration, and high performance. Experience creating interfaces for AI features such as chat systems, streaming responses, or semantic search. Understanding of localization, accessibility, security standards, and writing maintainable code. Experience using AI coding tools such as OpenAI Codex or Claude. Upper-Intermediate (B2) or higher English communication skills. Nice to Have Experience with React Flow, Highcharts, or similar visualization libraries. Basic backend knowledge in Node.js or Python and experience discussing API design. Experience with vector search, RAG interfaces, or semantic search solutions. Familiarity with MCP, DSPy, or other AI frameworks. Experience with monorepo tools such as Lerna, Turborepo, or Nx. Knowledge of AWS services like S3, CloudFront, and Lambda. Experience with Playwright, Puppeteer, or Cypress. What We Offer B2B contract and company stock options. MacBook Pro for work. Modern technology stack and opportunities to contribute to open-source projects. Access to advanced AI development tools, including GitHub Copilot, Claude Code, OpenAI Codex, TypingMind, v0, MCP Servers, and credits for testing new AI technologies. Our Values We believe our success comes from the way we work together: Quality – We aim for excellent work and high standards in everything we do. Momentum – We take initiative and keep projects moving forward. Accountability – We take responsibility and give honest, respectful feedback. Hard Work – We solve difficult problems together and stay committed to our goals. Learning – We are curious, improve every day, and learn from mistakes. Adaptability – We accept change and see challenges as opportunities. Teamwork – We communicate openly, support each other, and succeed as one team.

🏢 Summary: Frontend Engineer role focused on building enterprise AI applications using Next.js, React, and TypeScript in a fully on-site Warsaw office environment. The position involves developing real-time AI interfaces, managing complex frontend state, improving performance and accessibility, and contributing to technical decisions. Candidates will work with modern AI development tools and enterprise-scale frontend systems. 🗂️ Requirements: 3–5 years of frontend engineering experience, Strong knowledge of React, Strong knowledge of TypeScript, Strong knowledge of Next.js, Experience building production Next.js applications, Understanding of SSR, SSG, and CSR, Experience with complex state management, Experience with real-time updates and optimistic UI, Experience building AI or LLM-based interfaces, Understanding of frontend performance and Core Web Vitals, Knowledge of accessibility and localization, Security-focused development approach, Experience using AI coding assistants, Good communication skills, Ability to work fully on-site in Warsaw 📃 Skills: React, TypeScript, Next.js, SSR, SSG, CSR, AI, LLM, CoreWebVitals, Localization, Accessibility, Security, GitHubCopilot, OpenAI, Claude, ReactFlow, Highcharts, RAG, MCP, DSPy, Node.js, Python 🏢 Description: Please note: This role requires working from our office in Warsaw city centre 5 days a week . This is a fully on-site position , and remote or hybrid work is not available . About us We believe that businesses are moving toward AI-powered work, and we are building a platform for this future. Many AI agents cannot handle complex business tasks. We created a platform that organizes company policies, workflows, and business knowledge into one AI data model. This helps AI agents make accurate decisions and deliver reliable results at scale. We already work with well-known enterprise customers such as Glovo, Nespresso, and HelloFresh. Our platform supports thousands of users and processes real production data. Customers trust us with important business knowledge because we provide a secure and reliable solution with SOC2, HIPAA-ready security practices, and strong integrations. Job description We are looking for a frontend engineer with several years of experience who wants to build user interfaces for enterprise AI products. You will help create applications that allow users to work with AI systems in a simple and reliable way. You will build production applications using Next.js, work with complex application state, real-time AI features, and modern frontend technologies. Over time, you will also take part in important technical decisions. The position is based in Warsaw and requires working from the office. Responsibilities Build and deliver production Next.js applications with complex state management and real-time AI features. Create user interfaces for AI-powered tools, including streaming AI responses, semantic search, knowledge graphs, and AI agents. Help improve our component library and design system to keep the UI consistent, reusable, and accessible. Develop enterprise features such as localization, accessibility, browser compatibility, and security. Monitor applications after release, improve performance, reduce bundle size, and track Core Web Vitals. Use AI tools every day to improve development speed and internal frontend workflows. Maintain high code quality through testing and code reviews. Requirements Around 3–5 years of experience as a frontend engineer. Strong knowledge of React, TypeScript, and Next.js. Experience building production Next.js applications and understanding the differences between SSR, SSG, and CSR. Good experience with state management, including real-time updates, optimistic UI, and multi-tenant applications. Experience building AI or LLM-based interfaces such as chat applications, streaming responses, or semantic search. Good understanding of frontend performance, Core Web Vitals, and user experience. A security-focused approach and knowledge of accessibility and localization. Experience using AI coding assistants as part of your daily development work. Good communication skills and the ability to explain technical decisions clearly. Nice to have Experience with React Flow, Highcharts, or other data visualization libraries. Experience building vector search, RAG, or semantic search interfaces. Knowledge of MCP, DSPy, or other modern AI frameworks. Basic understanding of Node.js or Python backend development. Contributions to design systems or open-source UI libraries. What we offer B2B contract and company stock options. MacBook Pro. Modern technology stack and the opportunity to contribute to open-source projects. An AI-focused development environment with tools such as Claude Code, OpenAI Codex, and GitHub Copilot. Our values Our leadership team has strong experience in AI, knowledge management, and enterprise SaaS. We have received more than $60 million in funding and have been recognized by Gartner as a Cool Vendor. Our work is guided by these values: Quality – We care about excellent work and high standards in everything we build. Momentum – We take initiative, share ideas, and keep moving forward. Accountability – We take responsibility for our work and give honest, respectful feedback. Hard work – We believe success comes from teamwork, dedication, and consistent effort. Learning agility – We stay curious, learn from mistakes, and continue improving. Adapt and thrive – We welcome change and see challenges as opportunities to grow. Win together – We work as one team, communicate openly, and support our shared goals.

🏢 Summary: Senior Frontend Engineer role focused on building enterprise-grade AI-powered Next.js applications with complex state management, real-time features, and scalable frontend architecture. The position involves creating advanced AI interfaces, improving performance and accessibility, and contributing to design systems in a fully on-site Warsaw office environment. Candidates will work with modern AI development tools and enterprise-scale frontend technologies. 🗂️ Requirements: 5+ years of frontend development experience, 3+ years of React experience, Strong TypeScript skills, Production experience with Next.js, Knowledge of App Router, Knowledge of Server Components, Understanding of SSR, Understanding of SSG, Understanding of CSR, Experience with complex state management, Experience with real-time updates, Experience with optimistic UI, Experience with multi-tenant systems, Experience building AI or LLM interfaces, Knowledge of frontend performance optimization, Experience improving Core Web Vitals, Understanding of accessibility standards, Understanding of localization, Understanding of frontend security, Experience handling sensitive data, Experience using AI coding assistants, Strong communication skills, Ability to work fully on-site in Warsaw 📃 Skills: React, TypeScript, Next.js, SSR, SSG, CSR, AI, LLM, CoreWebVitals, Accessibility, Localization, Security, ReactFlow, Highcharts, Node.js, Python, RAG, OpenAI, Codex, GitHub, Copilot 🏢 Description: Please note: This role requires working from our office in Warsaw city centre 5 days a week . This is a fully on-site position , and remote or hybrid work is not available . About us We believe that businesses are moving toward AI-powered work, and we are building a platform for this future. Many AI agents cannot handle complex business tasks. We created a platform that organizes company policies, workflows, and business knowledge into one AI data model. This helps AI agents make accurate decisions and deliver reliable results at scale. We already work with well-known enterprise customers such as Glovo, Nespresso, and HelloFresh. Our platform supports thousands of users and processes real production data. Customers trust us with important business knowledge because we provide a secure and reliable solution with SOC2, HIPAA-ready security practices, and strong integrations. Job description We are looking for a Senior Frontend Engineer who enjoys building high-quality user interfaces for enterprise AI products. In this role, you will design and build important frontend features, solve complex UI problems, and improve the user experience over time. You will take ownership of frontend architecture and help build production Next.js applications with complex state management, real-time AI features, and enterprise functionality. The position is based in Warsaw and requires working from the office. Responsibilities Design and build production Next.js applications that support complex state, high traffic, and real-time AI features. Create user interfaces for AI-powered tools, including streaming AI responses, semantic search, knowledge graphs, and AI agents. Build and improve our component library and design system to keep the user experience consistent, accessible, and reusable. Deliver enterprise features such as localization, accessibility, browser compatibility, and security. Monitor applications after release, improve performance, reduce bundle size, track Core Web Vitals, and help systems scale. Maintain high engineering standards through code reviews, testing, and mentoring other developers. Requirements More than 5 years of frontend development experience, including at least 3 years working with React and modern TypeScript. Strong experience building production applications with Next.js, including App Router, Server Components, and understanding SSR, SSG, and CSR. Experience managing complex application state, including real-time updates, optimistic UI, multi-tenant systems, and large amounts of data. Experience building AI or LLM-based interfaces such as chat applications, streaming responses, or semantic search. Strong knowledge of frontend performance and experience improving Core Web Vitals in large applications. Good understanding of accessibility, localization, security, and enterprise application standards. A security-focused approach and experience working with sensitive data. Strong product thinking and the ability to improve user experience without waiting for detailed designs. Experience using AI coding assistants as part of your daily development work. Good written and spoken communication skills and the ability to explain technical decisions clearly. Nice to have Experience with React Flow, Highcharts, or other data visualization libraries. Experience building vector search, RAG, generative AI, or semantic search interfaces. Basic knowledge of Node.js or Python to understand backend code and APIs. Experience contributing to design systems or open-source UI libraries. What we offer B2B contract and company stock options. MacBook Pro. Modern technology stack and the opportunity to contribute to open-source projects. An AI-focused development environment with tools such as Claude Code, OpenAI Codex, and GitHub Copilot. Our values Our leadership team has strong experience in AI, knowledge management, and enterprise SaaS. We have received more than $60 million in funding and have been recognized by Gartner as a Cool Vendor. Our work is guided by these values: Quality – We care about excellent work and high standards in everything we build. Momentum – We take initiative, share ideas, and keep moving forward. Accountability – We take responsibility for our work and give honest, respectful feedback. Hard work – We believe success comes from teamwork, dedication, and consistent effort. Learning agility – We stay curious, learn from mistakes, and continue improving. Adapt and thrive – We welcome change and see challenges as opportunities to grow. Win together – We work as one team, communicate openly, and support our shared goals.