Senior Frontend React Developer

🏢 Summary: Senior Full Stack Engineer role focused on building and owning end-to-end product features for an AI-driven platform that automates complex business processes. The position involves developing frontend and backend solutions, designing APIs, improving performance and usability, and leveraging AI tools in daily engineering work. The role is office-based in Warsaw and requires strong product thinking and production-level experience. 🗂️ Requirements: Senior-level experience building production web applications, Strong knowledge of React and TypeScript or similar frontend framework, Experience designing and developing backend APIs and application logic, Ability to build and maintain frontend and backend features end-to-end, Experience working with production environments and monitoring released features, Daily use of AI tools for development and problem-solving, Strong understanding of code quality, testing, and long-term ownership 📃 Skills: React, TypeScript, JavaScript, API, REST, Node.js, Python, GitHub, Copilot, Claude, OpenAI, Codex, TypingMind, MCP, AI 🏢 Description: About the Role We are looking for a Senior Full Stack Engineer with strong product thinking. In this role, you will own features from start to finish. You will understand user needs, plan solutions, build frontend and backend functionality, release new features, and improve them based on user feedback. You should feel comfortable working on user interfaces, APIs, and production quality while collaborating with product and design teams. Location: Warsaw (office-based). Responsibilities - Build and deliver product features across both frontend and backend. - Turn product ideas into practical and effective solutions. - Work with user interfaces, business logic, APIs, and data flows. - Cooperate closely with product managers and designers, even when requirements are still developing. - Improve usability, performance, reliability, and overall user experience. - Monitor released features and use production data to make improvements. - Use AI tools every day to work faster and improve engineering processes. - Maintain high standards for code quality, testing, and long-term ownership. Requirements - Strong experience as a senior engineer building production web applications. - Good knowledge of React, TypeScript, or a similar modern frontend framework. - Experience designing and developing backend APIs and application logic. - Strong product mindset with the ability to identify and improve weak user experiences. - Good decision-making skills when balancing scope, speed, and technical quality. - Clear communication and teamwork across engineering, product, and design. - Daily experience using AI tools for development and problem-solving. Nice to Have - Experience building AI-powered products such as chat, search, recommendation systems, workflows, or AI agents. - Knowledge of Python, Node.js, or both. - Experience owning product areas independently. - Understanding of performance optimization, accessibility, and high-quality web applications. What We Offer - B2B contract and company stock options. - MacBook Pro for work. - Modern technology stack with opportunities to contribute to open-source projects. - Advanced AI development tools, including GitHub Copilot, Claude Code, OpenAI Codex, TypingMind, and MCP Servers. Why Join Us Our leadership team has strong experience in knowledge management and AI. We have raised more than $60 million in funding and achieved three years of continuous 3x growth. Our work is guided by these core values: - Quality: We aim for excellent craftsmanship and high standards in everything we build. - Momentum: We take initiative and keep projects moving forward. - Accountability: We take responsibility, give honest feedback, and support each other. - Hard Work: We believe difficult goals require dedication and teamwork. - Learning Agility: We stay curious, learn from mistakes, and keep improving. - Adapt and Thrive: We accept change and see challenges as opportunities. - Win Together: We succeed as a team through honesty, openness, and shared commitment.

🏢 Summary: Senior Frontend React Developer role focused on building and optimizing advanced UI applications with generative AI features in an enterprise environment. The position involves collaborating with cross-functional teams to deliver high-quality, user-centric solutions and integrating CI/CD and AI operational workflows. Hybrid work model based in Warsaw. 🗂️ Requirements: 4+ years of experience in React development, 4+ years of experience in JavaScript development, Strong knowledge of DevOps practices, Hands-on experience with Jira, Hands-on experience with GitLab, Hands-on experience with OpenShift, Proficiency in Linux, Experience with unit testing, Experience with system testing, Fluent Polish, Fluent English, Legal right to work in Europe 📃 Skills: React, JavaScript, DevOps, Jira, GitLab, OpenShift, Linux, CI/CD, Agile, Scrum, AI, Testing 🏢 Description: Empower innovation at the forefront of UI and AI technology — craft impactful user experiences that shape the future! Warszawa-based opportunity with hybrid work model (up to 2 remote days per week). As a Senior Frontend React Developer , you will be working for our client, a leader in enterprise software solutions, focusing on delivering cutting-edge UI and generative AI services. Join a collaborative, agile team committed to creating high-quality, user-centric applications that drive digital transformation and innovation. Your main responsibilities: Develop and optimize complex frontend applications using React and JavaScript, ensuring seamless user experiences Collaborate with cross-functional teams including data scientists and DevOps to deliver innovative UI solutions, including generative AI features Confirm technical designs, troubleshoot issues, and implement best practices for code quality and performance Contribute to the integration of CI/CD pipelines and operational workflows involving AI services Participate actively in Agile/Scrum ceremonies, promoting effective teamwork and continuous improvement You're ideal for this role if you have: 4+ years of proven experience in React and JavaScript development Strong understanding of DevOps practices with hands-on experience using Jira, GitLab, and OpenShift Proficiency in Linux OS and performing unit and system testing Excellent command of English, both written and spoken Ability to independently deliver high-quality code and confirm technical designs It is a strong plus if you have: (optional) Experience working with financial data, including Market Data and Reference Data Full-stack development expertise Knowledge of CI/CD pipelines and generative AI operational workflows Language Required for the role: Fluent in Polish and English Eligibility for the role: Only candidates with an existing legal right to work in Europe will be considered for this role. #MAKEYourCareerBETTER Interested? Apply now and include your CV (preferably in English) along with a statement confirming your consent to the processing and storage of your personal data.

🏢 Summary: Senior Backend Engineer responsible for designing, building, and maintaining production-grade backend systems that power AI-driven business automation. The role covers full ownership from system design to deployment, focusing on scalable, reliable distributed systems and cloud infrastructure. This is a Warsaw-based, office role with strong emphasis on technical leadership and AI-supported development workflows. 🗂️ Requirements: Senior-level experience in backend engineering on production systems, Strong Python programming skills, Experience with distributed systems concepts, Experience with cloud platforms (AWS, Azure, or similar), Knowledge of SQL and NoSQL databases, Ability to design, implement, and deliver systems to production, Strong written and spoken communication skills, Regular use of AI tools in development workflows 📃 Skills: Python, AWS, Azure, SQL, NoSQL, DistributedSystems, Concurrency, AsynchronousProcessing, APIs, Cloud, GitHubCopilot, OpenAI, Claude, TypeScript 🏢 Description: About Us Many companies want to use AI agents, but these agents often struggle with real business tasks. We solve this problem by building a platform that helps AI understand business rules, workflows, and processes. This allows AI to make better decisions and provide accurate, reliable, and compliant results. Well-known companies from different industries use our technology to automate up to 85% of customer cases, reduce handling time by 20–25%, and complete tasks that used to take hours in just seconds. We also work with leading technology partners and have been recognized for our innovative approach. Our goal is to help people everywhere get better answers through AI. Job Description We are looking for a Senior Backend Engineer who can take ownership of important systems instead of only completing assigned tasks. You will solve complex problems, design backend solutions, build them, and make sure they run well in production. We want someone with strong technical skills, good communication, and the ability to create simple, reliable, and easy-to-maintain systems. This is a product engineering role with responsibility from system design to production. The position is based in Warsaw and requires office work. Responsibilities - Design and develop backend services, APIs, data processing, and background tasks for production systems. - Turn unclear business needs into clear technical plans and practical solutions. - Maintain services after release by improving reliability, monitoring, performance, and fixing issues. - Make good decisions about system architecture, data models, interfaces, and future scaling. - Write technical documentation, architecture notes, and diagrams when they help the team. - Work closely with product managers, frontend engineers, and platform engineers to deliver complete solutions. - Improve development processes using AI tools, automation, and internal workflows. - Support the team through code reviews, design reviews, and practical technical leadership. Requirements - Strong experience as a senior backend engineer working on production systems. - Excellent Python skills and the ability to write clean and maintainable code. - Good understanding of distributed systems, including concurrency, failure handling, data consistency, asynchronous processing, and service design. - Experience with cloud platforms such as AWS, Azure, or similar services. - Knowledge of SQL, NoSQL databases, schema design, and performance optimization. - Ability to take a project from an idea through design and implementation to production. - Strong written and spoken communication skills with the ability to explain technical topics clearly. - Regular use of AI tools in everyday development and interest in improving AI-based workflows. Nice to Have - Experience with LLM-based applications, search systems, AI infrastructure, or large data pipelines. - Knowledge of TypeScript or the ability to contribute to frontend development when needed. - Experience guiding other engineers and influencing technical decisions without being a formal manager. 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, and MCP servers. Our Culture and Values Our leadership team has strong experience in AI and knowledge management. We have secured more than $60 million in funding and achieved three years of continuous 3x growth. Our work is based on these values: - Quality – We aim for excellent work and high coding standards. - Momentum – We take initiative and keep projects moving forward. - Accountability – We take responsibility and give honest, respectful feedback. - Hard Work – We believe great results come from teamwork and consistent effort. - Learning Agility – We stay curious, learn from mistakes, and improve every day. - Adapt and Thrive – We accept change and see challenges as opportunities. - Win Together – We succeed as one team through honesty, openness, and support for our shared mission.

🏢 Summary: The offer is for a Senior AI Fullstack Engineer to design and deliver production-ready, LLM-powered web applications using modern React and Next.js architecture. The role focuses on building autonomous agents, RAG systems, and AI-driven workflows integrated with enterprise-grade products. It involves end-to-end ownership of scalable AI solutions from architecture to deployment. 🗂️ Requirements: 8+ years experience as consultant or forward deployed engineer, Strong experience with Next.js (App Router), React, TypeScript, Deep understanding of Server and Client Components (RSC), Experience with streaming, caching, revalidation, Server Actions, Experience with Vercel AI SDK, LangGraph or MCP, Experience building RAG systems, Hands-on experience with Anthropic and OpenAI APIs, Experience shipping LLM-powered features to production, Practical experience with prompt engineering and structured outputs, Experience with tool calling and agent workflows, Experience with multi-turn orchestration, Understanding of token economics and context windows, Experience with prompt evaluation methods, Ability to design robust, production-ready AI systems 📃 Skills: Next.js, React, TypeScript, RSC, Vercel, LangGraph, MCP, RAG, Claude, OpenAI, Anthropic, Prompting, Streaming, ServerActions, Agents, APIs 🏢 Description: About the Role At Blazity, we are a team of React.js and Next.js experts building modern, API-first digital products for enterprise clients. We are expanding our AI capabilities—autonomous agents, AI-driven automation, and LLM-powered workflows—and are looking for a Senior AI Fullstack Engineer who can design and ship production-ready AI systems. You will work at the intersection of modern web architecture and generative AI , taking ownership of solutions delivered to real users. Our requirements Must-have Technical Excellence: 8+ years of experience as a consultant / forward deployed engineer Strong experience with Next.js (App Router), React, TypeScript Deep understanding of: Server vs Client Components (RSC) streaming, caching, revalidation, Server Actions Vercel AI SDK / LangGraph / MCP Experience building RAG systems Claude extended thinking / prompt caching / Batch APIs AI Engineering: Proven experience shipping LLM-powered features to production Hands-on with Anthropic / OpenAI APIs (messages, tool use, streaming) Practical experience with: prompt engineering (structured output, few-shot, XML) tool calling / agent workflows multi-turn orchestration Understanding of: token economics (input/output costs, context window) latency vs quality trade-offs Reliability & Quality: Experience with: prompt evaluations (LLM-as-judge, rule-based) handling hallucinations and failure modes Ability to design robust AI systems , not just prototypes Soft Skills: Strong ownership mindset Experience working directly with clients Clear communication and structured thinking (English C1) Ability to make decisions in ambiguous environments Nice-to-have: What You Will Do Ship Production Apps: Build scalable web applications using Next.js (App Router) and TypeScript , ensuring high performance and clean architecture. Engineer AI Workflows: Develop and orchestrate LLM-powered features using Anthropic and OpenAI APIs, focusing on tool use and streaming. Agentic Orchestration: Design autonomous agent loops and multi-turn workflows, knowing when to use a structured pipeline versus a dynamic agent. Optimize & Evaluate: Manage token economics (pricing, context windows) and implement prompt evaluations (LLM-as-judge, rule-based) to ensure system reliability. Collaborate: Work directly with senior engineers, founders, and client teams to shape AI capabilities from concept to production. What we offer B2B: 120 – 180 PLN/h + VAT 🔥 100% remote (Poland) 29 paid vacation days Private healthcare + sports card High-impact work on real AI systems

🏢 Summary: Frontend Engineer role focused on building production-ready Next.js SSR applications that power enterprise AI interfaces at scale. The position involves architecting complex state management, real-time LLM streaming experiences, and high-performance data-heavy UIs integrated with enterprise systems. You will own features end-to-end, ensuring accessibility, security, and performance for mission-critical AI-driven workflows. 🗂️ Requirements: 5+ years frontend engineering experience, 3+ years experience with React and modern JavaScript/TypeScript, Production experience with Next.js SSR applications, Advanced TypeScript expertise, Experience with complex state management in real-time or multi-tenant applications, Experience building enterprise applications with i18n, accessibility, and security standards, Experience building AI/LLM interfaces with streaming or real-time interactions, Proven ability to optimize high-load, data-heavy applications, Strong expertise in modern CSS (Tailwind CSS or CSS-in-JS), Experience with observability and monitoring tools, Experience using AI coding assistants in development, Upper-Intermediate English proficiency 📃 Skills: React, Next.js, TypeScript, JavaScript, SWR, REST, WebSockets, Tailwind, CSS, Storybook, ReactFlow, Highcharts, Playwright, Datadog, Sentry, Elasticsearch, DynamoDB, PostgreSQL, Aurora, AI, LLM 🏢 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: 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: Frontend-leaning Fullstack Engineer role building high-scale SaaS systems with modern React/Next.js frontends and Node.js/NestJS backends, heavily leveraging AI tools and automation. You will design APIs, async systems, and event-driven architectures, integrate external services, and ship MVPs to production with ownership and speed. The role emphasizes AI-driven workflows, rapid experimentation, and scalable, production-ready systems. 🗂️ Requirements: 2.5+ years professional full-stack experience, Strong React.js and Next.js skills, Backend experience with Node.js (NestJS preferred), Experience integrating external APIs (auth, pagination, retries, rate limits), Hands-on experience with modern AI tools (OpenAI, Claude, Cursor), Strong SQL skills (PostgreSQL preferred), Experience with async processing, queues, background jobs, Understanding of reliable systems (error handling, retries, observability), Fluent English and Polish 📃 Skills: React, Next.js, Node.js, NestJS, SQL, PostgreSQL, REST, WebSockets, OpenAI, Claude, Cursor, LavinMQ, BullMQ, Kafka, AWS, GCP, Fly.io, DigitalOcean, BigQuery, ClickHouse, Golang, Elixir, Rust, gRPC, GitLabCI 🏢 Description: At Web Impact, we’re more than just an email marketing agency and digital solutions provider. We build cutting-edge, socially impactful products that redefine how businesses operate in the digital world. We’re looking for a frontend-leaning Fullstack Engineer who enjoys building complex systems, integrating external services, and leveraging AI tools to speed up development and automate workflows. If you’re excited about combining modern frontend development with AI-driven workflows and automation tools like Claude Code, Cursor, and LLM frameworks , this one is for you. What You’ll Do Develop and contribute to end-to-end features across SaaS products and internal tools, collaborating with senior engineers on architecture and implementation decisions. Build modern, high-performance frontends using Next.js and React.js Develop scalable backend services using Node.js / NestJS Design and integrate APIs (REST, WebSockets, external services) Build and maintain automation workflows and background jobs Work with async systems, queues, and event-driven architectures Integrate third-party services with real-world constraints (rate limits, retries, auth flows) Use AI tools to improve development speed, testing, and automation Collaborate directly with product, data, and leadership teams Build MVPs, proof-of-concepts, and new product ideas from scratch Rapidly validate business ideas through experimentation and iteration Help evolve successful prototypes into production-ready systems AI & Automation This role includes working with modern AI tooling and automation systems, with a strong focus on speed, ownership, and execution : Using tools like Claude Code, Cursor, and OpenAI SDK in daily development Building AI-driven workflows and integrations quickly and iteratively Automating repetitive processes (data handling, content, integrations) Applying LLMs in production with a pragmatic, results-first approach Taking ownership of problems - from idea to production Shipping fast, testing in real conditions, and iterating based on outcomes Being accountable for delivery - not just writing code, but making things work end-to-end Prioritizing execution over perfection - speed is key What We’re Looking For 2,5+ years of professional full-stack experience Strong frontend skills in React.js / Next.js Backend experience with Node.js (NestJS preferred) Experience integrating external APIs (auth, pagination, retries, rate limits) Hands-on experience with modern AI tools (OpenAI, Claude, Cursor, etc.) Good SQL skills (PostgreSQL preferred) Experience working with async processing, queues, and background jobs Understanding of building reliable systems (error handling, retries, observability) Strong communication skills and ability to work cross-functionally Fluent in English and Polish Nice to Have Experience with Rust (async, Tokio, Axum) Experience with Elixir (Phoenix LiveView, GenServer) Understanding of distributed systems and architectures Experience with multi-region deployments and geo-distributed infrastructure Experience building systems with high parallelism (a large number of workers processing jobs concurrently) Familiarity with distributed databases and data consistency trade-offs Experience with multi-tenancy architectures (tenant isolation, scaling strategies) Experience working with high-throughput event pipelines Our Tech Stack Frontend: Next.js, React.js Backend: Node.js, NestJS, Golang, Elixir, Rust Data: PostgreSQL, BigQuery, ClickHouse Infra: AWS, Fly.io , Google Cloud, DigitalOcean Queues & Workers: LavinMQ, BullMQ, Kafka CI/CD: GitLab CI AI/ML & Automation: Proprietary GenAI models, OpenAI, Claude, internal tooling Integrations: REST, gRPC, WebSockets, external APIs with rate limits Why Join Us? Work on high-scale SaaS systems processing hundreds of millions of events daily , with real-time pipelines and data-heavy workloads. Ownership from day one - influence architecture, technology choices, and product direction. Collaborate with world-class engineers, AI specialists, and PMs. Innovation-first culture - explore cutting-edge frameworks and architectures. Fast execution, minimal bureaucracy, no unnecessary meetings Opportunity to work with modern AI tooling in production Competitive senior-level compensation and career growth. Social impact - contribute to automation products that empower businesses and communities. Our Streamlined Hiring Process Initial call Technical deep dive with our team Decision

🏢 Summary: Mid/Senior React Developer role focused on end-to-end frontend feature delivery using strict TypeScript, shared cross-platform architecture, and AI-augmented workflows. The position emphasizes monorepo-based unified codebases, strong testing discipline, performance optimization aligned with Core Web Vitals, and secure coding practices. The developer owns code quality, performance, and maintainability across Web and Mobile platforms. 🗂️ Requirements: Strong React experience with lifecycle and hooks, Production experience with strict TypeScript, Experience with monorepo tools (Turborepo or Nx), Ability to build shared cross-platform components and abstractions, Unit and integration testing with Vitest or Jest, Proficiency with React Testing Library, Understanding of Core Web Vitals (LCP, INP, CLS) optimization, Experience with performance profiling and optimization techniques, Knowledge of OWASP Top 10 and frontend security practices, Experience using AI tools or agents to enhance development workflow 📃 Skills: React, TypeScript, JavaScript, Turborepo, Nx, Vitest, Jest, TestingLibrary, AI, LCP, INP, CLS, OWASP, ReactNative, Monorepo, WebPerformance, Security 🏢 Description: We are seeking a skilled Mid/Senior React Developer to join our team. Responsibilities Feature Delivery & Code Quality Own end-to-end delivery of frontend features from UI/UX implementation to complex business logic. Write production-grade TypeScript with strict type safety and comprehensive test coverage Participate in code reviews with a focus on maintainability, performance, security, and accessibility. Unified Codebase Contribution Develop shared components, hooks, and utilities that work across Web and Mobile platforms Ensure code reusability through proper abstraction and monorepo discipline Collaborate with architects to identify opportunities for cross-platform unification Document patterns and decisions for team knowledge sharing AI-Augmented Development Leverage AI-powered workflows to accelerate repetitive tasks: refactoring, test generation, code profiling Use agents for code review assistance, documentation generation, and debugging Continuously optimize your development velocity through appropriate AI tooling Share effective workflows with the team to elevate collective productivity Performance Ownership Treat performance as an architectural constraint, not a post-hoc optimization Monitor and improve Core Web Vitals (LCP, INP, CLS) for web applications Qualifications React Production Experience Deep understanding of React lifecycle, hooks patterns, and performance optimization. Experience with strict TypeScript in real codebases. AI Augmentation Proficiency Demonstrated experience using AI agents to enhance development workflow. Ability to articulate specific examples of how you've used AI tools to improve productivity Understanding of when AI assistance adds value and when manual approaches are more appropriate. Familiarity with agent orchestration concepts beyond basic autocomplete. Monorepo & Unified Codebase Mindset Experience with Turborepo, Nx, or similar tools. Understanding of shared logic, types, and component patterns across platforms. Testing Discipline Unit and integration testing with Vitest or Jest. React Testing Library proficiency. Commitment to maintaining test coverage on critical paths. Performance Engineering Mindset Understanding of Core Web Vitals (LCP, INP, CLS) and their optimization strategies. Ability to articulate the business impact of performance. Experience with performance budgets, profiling tools, and optimization techniques. For candidates declaring React Native experience: awareness of bridge overhead, list virtualization, and memory management. Security Awareness Understanding of OWASP Top 10 and common frontend security vulnerabilities. Secure coding practices for authentication, authorization, and data handling. Awareness of dependency security and supply chain risks. Language Skills & others English B2+ (mandatory) for technical documentation and cross-team collaboration. Readiness to work from our Warsaw office at least 1 day per week. Benefits Unique TEAL culture, relationship- and respect-driven community, non-corporate atmosphere. Agile approach and no bureaucracy. Outstanding integration trips to various places in Europe for all employees. Activities to support your well-being and health. Luxmed Gold Extended medical care and Multisport Plus benefit. Engagement in innovative projects within a supportive and collaborative environment. Flexible working arrangements to promote work-life balance. Access to modern tools and technologies to enhance productivity.

🏢 Summary: Frontend-leaning Fullstack Engineer role focused on building and owning end-to-end SaaS features using modern frontend frameworks, scalable backend services, and AI-driven automation tools. The position combines React/Next.js development with Node.js backend work, async systems, and production AI integrations. Strong emphasis on speed, ownership, and delivering reliable, high-scale systems. 🗂️ Requirements: 3+ years professional full-stack development experience, Strong proficiency in React.js and Next.js, Solid backend experience with Node.js (NestJS preferred), Experience integrating external APIs (authentication, pagination, retries, rate limits), Experience with asynchronous processing, queues, and background jobs, Hands-on experience with AI tools (OpenAI, Claude, Cursor), Strong SQL skills (PostgreSQL preferred), Experience building reliable systems (error handling, retries, observability), Fluent English and Polish 📃 Skills: React, Next.js, Node.js, NestJS, JavaScript, TypeScript, PostgreSQL, SQL, REST, WebSockets, gRPC, Kafka, BullMQ, LavinMQ, AWS, GCP, DigitalOcean, Fly.io, GitLab, OpenAI, Claude, Cursor, Golang, Elixir, Rust, BigQuery, ClickHouse 🏢 Description: At Web Impact, we’re more than just an email marketing agency and digital solutions provider. We build cutting-edge, socially impactful products that redefine how businesses operate in the digital world. We’re looking for a frontend-leaning Fullstack Engineer who enjoys building complex systems, integrating external services, and leveraging AI tools to speed up development and automate workflows. If you’re excited about combining modern frontend development with AI-driven workflows and automation tools like Claude Code, Cursor, and LLM frameworks , this one is for you. What You’ll Do Own and deliver end-to-end features across SaaS products and internal tools Build modern, high-performance frontends using Next.js and React.js Develop scalable backend services using Node.js / NestJS Design and integrate APIs (REST, WebSockets, external services) Build and maintain automation workflows and background jobs Work with async systems, queues, and event-driven architectures Integrate third-party services with real-world constraints (rate limits, retries, auth flows) Use AI tools to improve development speed, testing, and automation Collaborate directly with product, data, and leadership teams AI & Automation This role includes working with modern AI tooling and automation systems, with a strong focus on speed, ownership, and execution : Using tools like Claude Code, Cursor, and OpenAI SDK in daily development Building AI-driven workflows and integrations quickly and iteratively Automating repetitive processes (data handling, content, integrations) Applying LLMs in production with a pragmatic, results-first approach Taking full ownership of problems - from idea to production Shipping fast, testing in real conditions, and iterating based on outcomes Being accountable for delivery - not just writing code, but making things work end-to-end Prioritizing execution over perfection - speed is key What We’re Looking For 3+ years of professional full-stack experience Strong frontend skills in React.js / Next.js Solid backend experience with Node.js (NestJS preferred) Experience integrating external APIs (auth, pagination, retries, rate limits) Experience working with async processing, queues, and background jobs Hands-on experience with modern AI tools (OpenAI, Claude, Cursor, etc.) Good SQL skills (PostgreSQL preferred) Understanding of building reliable systems (error handling, retries, observability) Strong communication skills and ability to work cross-functionally Fluent in English and Polish Nice to Have Experience with Rust (async, Tokio, Axum) Experience with Elixir (Phoenix LiveView, GenServer) Understanding of distributed systems and architectures Experience with multi-region deployments and geo-distributed infrastructure Experience building systems with high parallelism (a large number of workers processing jobs concurrently) Familiarity with distributed databases and data consistency trade-offs Experience with multi-tenancy architectures (tenant isolation, scaling strategies) Experience working with high-throughput event pipelines Our Tech Stack Frontend: Next.js, React.js Backend: Node.js, NestJS, Golang, Elixir, Rust Data: PostgreSQL, BigQuery, ClickHouse Infra: AWS, Fly.io , Google Cloud, DigitalOcean Queues & Workers: LavinMQ, BullMQ, Kafka CI/CD: GitLab CI AI/ML & Automation: Proprietary GenAI models, OpenAI, Claude, internal tooling Integrations: REST, gRPC, WebSockets, external APIs with rate limits Why Join Us? Work on high-scale SaaS systems processing hundreds of millions of events daily , with real-time pipelines and data-heavy workloads. Ownership from day one - influence architecture, technology choices, and product direction. Collaborate with world-class engineers, AI specialists, and PMs. Innovation-first culture - explore cutting-edge frameworks and architectures. Fast execution, minimal bureaucracy, no unnecessary meetings Opportunity to work with modern AI tooling in production Competitive senior-level compensation and career growth. Social impact - contribute to automation products that empower businesses and communities. Our Streamlined Hiring Process Initial call Technical deep dive with our team Decision

🏢 Summary: The offer is for a Senior Frontend Developer responsible for building and maintaining user interfaces using React within AI-powered business platforms. The role focuses on developing high-quality, scalable front-end solutions with strong emphasis on TDD, performance, and cross-team collaboration. Candidates will work in an Agile environment delivering robust, user-friendly products. 🗂️ Requirements: 6+ years of experience with JavaScript and TypeScript, Strong knowledge of React.js and Redux, Understanding of JavaScript design patterns, Knowledge of functional programming, Knowledge of asynchronous programming, Experience with Git and branch management, Ability to debug front-end issues using debugging tools, Experience creating and integrating custom packages, Understanding of object-oriented programming in JavaScript, Hands-on experience with HTML5 and CSS3, Experience with Test-Driven Development (TDD), Experience with Continuous Integration, Familiarity with Agile development practices, Ability to write cross-browser compatible code 📃 Skills: JavaScript, TypeScript, React, Redux, Next.js, HTML5, CSS3, Git, TDD, CI, Agile 🏢 Description: Overview We are a company that leads in AI-powered business operations, providing digital solutions and consulting services that help businesses grow and improve. We focus on using advanced technology to make operations easier, increase efficiency, and create new opportunities, especially in private capital markets. Our services include: PaaS (Platform as a Service): Our main platform uses AI to improve workflows, generate insights, and help businesses grow faster. SaaS (Software as a Service): A cloud platform that offers strong performance, smart tools, and large-scale execution. S&C (Solutions and Consulting Suite): Flexible technology tools to manage, develop, and improve business performance. With over ten years of experience helping fast-growing companies and private equity-backed businesses, we bring deep knowledge and a proven track record of turning technology into a real advantage. Responsibilities Design and develop user interfaces using React. Implement and maintain test-driven development (TDD) and continuous integration. Work with project managers, analysts, and sales teams to deliver high-quality products on time. Follow best practices in testing, accessibility, and performance. Work closely with design, backend, QA, and product teams to build user-friendly solutions. Requirements 6+ years experience with JavaScript and TypeScript. Understand design patterns and how to use them in JavaScript. Experience with modern front-end frameworks like React.js + Redux; Next.js is a bonus. Knowledge of functional and asynchronous programming. Experience with Git and branch management. Ability to debug front-end issues and use debugging tools. Familiar with creating and integrating custom packages. Understand object-oriented programming concepts in JavaScript. Can work under pressure and meet tight deadlines. Hands-on experience with HTML5 and CSS3. Familiar with Agile development practices. Good communication and organizational skills. Able to write code that works across different browsers. Bachelor’s degree in Computer Science or similar is preferred. Why Join Us? We appreciate creative problem-solvers who learn quickly, work well in a diverse environment, and like to raise the standard for success. We work hard but also make sure to enjoy what we do.