Senior Frontend Engineer (React)

🏢 Summary: Frontend Engineer role focused on building production-grade Next.js applications with real-time AI interactions, semantic search, and interactive knowledge graphs for enterprise-scale AI software products. The position involves working with React and TypeScript, contributing to design systems, optimizing frontend performance, and supporting accessibility and security requirements. Candidates will also use AI coding assistants in daily workflows and maintain high standards for code quality and test coverage. 🗂️ Requirements: 3-5 years frontend engineering experience, React, TypeScript, Next.js, SSR/SSG/CSR knowledge, State management, Real-time UI updates, AI/LLM interface experience, Semantic search interfaces, Frontend performance optimization, Core Web Vitals, Accessibility, Localization, Security practices, Cross-browser compatibility, AI coding assistants, Code review, Test coverage, Technical communication 📃 Skills: React, TypeScript, Next.js, SSR, SSG, CSR, LLM, AI, SemanticSearch, CoreWebVitals, Accessibility, Security, Localization, ReactFlow, Highcharts, MCP, DSPy, Node.js, Python, RAG 🏢 Description: Frontend Engineer (React) Salary: 5,000-7,000 USD per month Hybrid, 1 day remote Full-time B2B We're looking for a Frontend Engineer for a leading enterprise AI software provider. You'll build production Next.js applications with real-time AI interactions, including streaming LLM responses, semantic search, and interactive knowledge graphs. You'll also contribute to the design system, handle enterprise requirements such as accessibility and security, and own post-launch performance. The team serves enterprise customers at scale, maintains SOC 2 compliance with HIPAA-ready security, and uses AI coding assistants daily in their development process. Requirements - 3-5 years in frontend engineering, with solid React and modern TypeScript skills - Hands-on Next.js production experience, having shipped SSR applications and understanding the trade-offs among SSR, SSG, and CSR - Strong grasp of state management, including some exposure to real-time updates, optimistic UI, or multi-tenant data - Prior work on AI/LLM interfaces, such as streaming responses, chat UIs, or semantic search - Practical understanding of frontend performance, including Core Web Vitals and common optimization methods - Some background in enterprise application needs: localization, accessibility, security practices - A security-minded approach to development, with care around sensitive data and awareness of security implications - Solid product and UX judgment, able to spot issues and propose fixes - Regular use of AI coding assistants as part of daily workflow - Ability to explain design and technical decisions clearly, both in writing and verbally Nice to Have - Experience with React Flow, Highcharts, or similar data-visualization libraries - Direct experience with vector search UIs, RAG interfaces, or semantic search systems - Familiarity with MCP, DSPy, or other current AI frameworks, and experience building agentic AI interfaces - Basic understanding of Node.js/Python backend concepts, enough to read backend code and participate in API design discussions - Past contributions to design systems or open-source component libraries Responsibilities - Design and deploy production-ready Next.js applications handling complex state and live AI interactions - Develop interfaces for AI features, including streaming LLM output, semantic search, interactive knowledge graphs, and agentic builders - Support and extend the component library and design system, ensuring reusability, accessibility, and consistency - Handle enterprise-level requirements such as localization, accessibility, cross-browser compatibility, and security practices - Take responsibility for shipped features after launch: track performance, reduce bundle size, and monitor Core Web Vitals - Apply AI tools in daily work to increase speed, and contribute to improving internal frontend processes - Uphold high standards for code quality and test coverage via careful code review

🏢 Summary: Full-time, 100% remote Senior Frontend Developer role focused on building and scaling complex, responsive web applications powered by AI-driven platforms. The position involves architecting high-quality front-end solutions, integrating with back-end services, and ensuring performance, scalability, and cross-browser compatibility. The role also includes driving best practices, code quality, and modern front-end standards within the team. 🗂️ Requirements: Strong knowledge of HTML5, CSS3, JavaScript (ES6), Strong understanding of DOM, Experience with React.js, Experience with Material UI, Experience with Responsive Design and cross-browser compatibility, Familiarity with SASS or LESS, Understanding of BEM methodology, Knowledge of CSS-in-JS, Knowledge of browser storage (cookies, localStorage, sessionStorage), Proficiency with npm or yarn, Experience with Jest or equivalent testing frameworks, Understanding of SEO best practices, Familiarity with TypeScript, Knowledge of SSR and service workers, Experience with Webpack, Vite, or Rollup, Understanding of browser extensions integration 📃 Skills: HTML5, CSS3, JavaScript, ES6, DOM, React, MaterialUI, SASS, LESS, BEM, CSS-in-JS, cookies, localStorage, sessionStorage, npm, yarn, Jest, TypeScript, SSR, Webpack, Vite, Rollup, SEO, ServiceWorkers 🏢 Description: Senior Frontend Developer (100% remote) 💰 Salary: 20,000-23,000 PLN/month 🌎 100% Remote 🕦 Full-time position ☑️ B2B or Contract of Employment We are looking for a Senior Frontend Developer for a partner client that helps businesses use artificial intelligence to run more efficiently and grow faster. The company builds and provides digital platforms and consulting services that enable organizations to manage operations, analyze data, and improve performance. Their solutions combine AI, automation, and deep business expertise to help clients simplify workflows, gain insights, and deliver greater value. Requirements: HTML5 , CSS3 , JavaScript (ES6) Strong understanding of the Document Object Model (DOM) Skilled in Responsive Design and cross-browser compatibility Experience with React.js and Material UI Familiarity with CSS preprocessors such as SASS or LESS Understanding of BEM methodology and CSS-in-JS approaches Knowledge of browser storage mechanisms (cookies, localStorage, sessionStorage) Proficient in using package managers (npm/yarn) Experience in unit testing using Jest or equivalent frameworks Understanding of SEO best practices Familiarity with TypeScript for type-safe, large-scale applications Knowledge of server-side rendering (SSR) and service workers Experience with code bundling and modern module bundlers (e.g., Webpack, Vite, Rollup) Understanding of browser extensions and their integration with web applications Responsibilities: Develop and maintain  complex, responsive user interfaces for large-scale web applications. Architect and integrate front-end components with back-end APIs and services , ensuring security, scalability, and performance. Drive the implementation of pixel-perfect UI/UX designs across browsers and devices. Provide technical mentorship to junior developers and guide the team in adopting modern best practices. Conduct code reviews , enforce standards, and maintain a clean, modular codebase. Evaluate and recommend new frameworks, tools, and libraries to enhance productivity. Manage project timelines, estimate development efforts, and collaborate effectively with cross-functional teams. Maintain comprehensive front-end documentation , design patterns, and style guides. Stay updated with industry trends , emerging technologies, and front-end innovations to continuously improve team capabilities. Participate in architectural discussions , ensuring long-term scalability and maintainability of the front-end ecosystem. Get to know DevsData We are a technology consulting company and a recruitment agency, delivering software solutions to clients from Europe and the US. We work 100% remotely, in an international team, including people from Asia, London, or San Francisco. We employ people with experience in international corporations as well as students of the best technical and business universities. Find out more: https://devsdata.com

🏢 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.

🏢 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: Full-stack Engineer role building and shipping end-to-end features for a health-tech AI product, covering internal clinician tooling and a client-facing app. The position involves integrating diagnostics, wearable and lab data, and leveraging AI coding agents as a core part of the development workflow. Engineers are expected to own architecture decisions, security, and delivery across the full stack in a fast-moving remote environment. 🗂️ Requirements: 4+ years professional software engineering experience, At least two shipped products used by real users, Strong Computer Science fundamentals (data structures, systems, software design), Experience with both backend and frontend development, Daily use of AI coding agents in development workflow, Experience with strict typing, linting, and automated testing, Ability to design and implement secure architectures, Availability during Central European morning hours, Fluent English for technical communication 📃 Skills: Fullstack, Backend, Frontend, APIs, Security, AI, Testing, Linting, Typing, Databases, Wearables, Integration 🏢 Description: 💰 Salary: $5,000-$7,000/month (depending on seniority) 🌎 100% remote 🕦 Full-time position, long-term ☑️ B2B contract We are looking for a Full-stack Engineer to join our client, a Singapore-headquartered health-technology and AI startup focused on longevity and preventative care. The product combines diagnostics, wearable signals, lab data, and AI to coordinate personalised health programmes for individual clients. You will own features end-to-end across two surfaces: internal tooling used by in-house clinicians to assemble recommendations, and the client-facing app that turns those recommendations into daily actions. AI coding agents are part of the daily workflow, and every engineer is expected to push what these tools can do, not treat them as autocomplete. The tech stack is intentionally not fixed; the bar is engineering judgement and shipping speed. Requirements 4+ years of professional software engineering experience, with at least two products shipped to real users Computer Science background, or an equivalent track record that shows the same depth in data structures, systems, and applied software design Strong fundamentals across both server and client work, regardless of which language or framework you used most recently Daily use of AI coding agents in your workflow, with an honest read on where they currently help and where they fail Comfort with strict typing, linting, automated tests, and the rest of a modern production setup Reliable availability during Central European morning hours, so meetings line up with Singapore afternoons Fluent English for technical discussions and written documentation Responsibilities Build and ship features across the full stack, from schema design through to the final UI details Develop the internal dashboards used by medical practitioners to interpret client data and assemble recommendations Develop the client-facing application that delivers daily health guidance to end users Design and tune the security posture separately for internal practitioner tooling and external consumer surfaces Integrate inputs from wearables, lab providers, and the physical clinic environment into one coherent product Push the AI tooling stack hard, both as part of the development process and inside product features Operate as a product-minded engineer: spot problems early, propose solutions, and drive them through to release Get to know DevsData We are a technology consulting company and a recruitment agency, delivering software solutions to clients from Europe and the US. We work 100% remotely, in an international team. We employ people with experience in international corporations as well as the ones from the best technical and business universities. Find out more: https://devsdata.com

🏢 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: 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: Senior Lead Engineer role focused on leading architecture and delivery of high-scale enterprise systems using React, Node.js, and TypeScript, while integrating advanced AI agents into deterministic workflows. The position combines hands-on development, technical leadership, and ownership of mission-critical systems in close collaboration with AI architects. It offers high impact on production-ready AI solutions for global enterprises. 🗂️ Requirements: 10+ years of software engineering experience, Proven experience in Lead, Principal, or Expert engineering roles, Expert-level knowledge of React, Expert-level knowledge of Node.js, Expert-level knowledge of TypeScript, Experience designing and scaling enterprise systems, Experience conducting code reviews and mentoring engineers, Ability to integrate AI/LLM agents into enterprise systems, Strong problem-solving skills for complex production issues, English proficiency at minimum B2 level 📃 Skills: React, Node.js, TypeScript, JavaScript, LLM, AI, Neurosymbolic, State, Machines, Python, NX, Snowflake 🏢 Description: Position: Senior Lead Engineer (React, Node.js & AI) Location: Kraków (On-site) Salary: 35,000 – 45,000 PLN net + VAT (B2B) + 10% yearly performance bonus About the Project Our Client is an innovative software company specializing in transforming raw AI capabilities into durable, deterministic enterprise systems. Known for their elite engineering culture, they specialize in delivering high-scale, production-ready AI solutions for global Fortune 500 enterprises. As a Senior Lead Engineer, you will become the right hand to the Principal Architect. This is a high-impact, operational leadership role where you will take full accountability for core React/Node/TS interfaces and backend systems, mentor the engineering team, and seamlessly integrate cutting-edge AI agents into complex enterprise workflows. Your leadership will drive delivery, allowing the Principal Architect to focus entirely on macro-level AI strategies and frontier models. Your Role Architecture & Delivery: Designing, building, and scaling core enterprise systems and interfaces using React, Node.js, and TypeScript. Technical Leadership: Taking extreme ownership of the codebase, enforcing world-class standards, conducting code reviews, and mentoring the engineering team to help them grow into independent problem solvers. AI Integration: Collaborating closely with the AI architecture team to embed LLM agents, neurosymbolic systems, and state machines into secure, deterministic enterprise workflows. Problem Solving: Acting as the ultimate escalation point for complex technical challenges, leading the charge to unblock production when critical issues arise. Strategic Execution: Translating high-level business requirements and macro-architecture directly into flawless, high-performing code that creates durable operating leverage. Requirements Experience: 10+ years of hard-core software engineering experience, with a proven track record in Lead, Principal, or Expert roles. Tech Stack Mastery: Absolute, atomic-level expertise in React, Node.js, and TypeScript ecosystem. Extreme Ownership: A proactive mindset – you don’t wait for tasks; you identify problems, design solutions, align resources, and deliver with absolute certainty. Leadership & Mentoring: Ability to elevate the team, set uncompromising quality standards, and guide junior/mid engineers. Business DNA: Deep understanding that code serves tangible business goals (ROI) and creates long-term value, rather than just being technical art. Communication: English at minimum B2 level to collaborate effectively with an elite team and global partners. Nice to have Practical experience or strong interest in Python, NX, and Snowflake. Hands-on exposure to frontier AI/LLM models and agents. What We Offer Global Impact: The chance to build next-generation neurosymbolic systems redefining how global enterprises utilize AI. Elite Environment: Direct collaboration alongside C-level executives, visionaries, and core software architects. High-End Hardware: New Apple MacBook Pro and external monitors provided as needed. Flexible Culture: Flexible working hours within a modern, fully-equipped office setup. Premium Office Perks: Access to a modern office in Kraków featuring a playroom, bike parking, shower, free coffee, beverages, and snacks (with no dress code). Growth & Benefits: Dedicated conference budget to support your continuous professional development.

🏢 Summary: Part-time, fully remote Senior Frontend Developer role focused on maintaining, optimizing, and incrementally improving a large, production-grade public website. The position centers on performance optimization, legacy code maintenance, and enhancing user-facing features within an existing WordPress-based system. The work emphasizes stability, speed, SEO best practices, and cross-browser compatibility rather than full rewrites. 🗂️ Requirements: Expert-level front-end development experience, Proven experience with long-lived or legacy codebases, Strong website performance optimization experience, Experience with web performance audits and tooling, Excellent knowledge of JavaScript, Excellent knowledge of HTML, Excellent knowledge of CSS, Understanding of responsive design principles, Basic understanding of SEO fundamentals and performance factors, Experience working with large frontend systems, Ability to work independently 📃 Skills: JavaScript, HTML, CSS, PHP, WordPress, CloudFlare, Lighthouse, GooglePageSpeed, SEO 🏢 Description: Senior Frontend Developer (Part-time; 100% remote) 💰Salary: up to around $40 per hour 💻 100% Remote 🕦 Part-time: Around 10h per week, up to 10-15h/week, as needed ☑️ B2B contract/freelance We are seeking a Senior Front-End Developer to work on the ongoing improvement, maintenance, and optimization of our extensive public-facing website. The role is focused on working with an existing, production-grade codebase built primarily with HTML, CSS, JavaScript, PHP and WordPress, under CloudFlare. Requirements Expert-level experience in front-end development, with a strong track record of working on long-lived or legacy codebases Website performance optimization experience, web performance tooling and audits (e.g., Lighthouse, Google PageSpeed insights) experience. Ability to work independently (along with a work history of independent work) Excellent knowledge of JavaScript, HTML and CSS, with a clear understanding of responsive design principles Basic understanding of SEO fundamentals, including performance factors, and search-engine-friendly markup Experience working with extensive and legacy frontend systems Strong attention to detail and a quality-focused mindset Main Responsibilities Optimize page load times and overall website performance using front-end techniques. Working on bugfixes and optimization of a legacy front-end website built with JavaScript, HTML, CSS, and WordPress, ensuring performance, and stability. Improve existing features and user-facing functionality through thoughtful, incremental enhancements rather than full rewrites. Collaborate with internal developers, designers, management, and content teams to implement updates and refinements to existing pages and components. Ensure cross-browser compatibility across the website. Apply front-end SEO best practices, including performance optimization (most importantly), accessibility improvements, page structure, and Core Web Vitals. Get to know DevsData: We are a technology consulting company and a recruitment agency, delivering software solutions to clients from Europe and the US. We work 100% remotely, in an international team, including people from Asia, London, or San Francisco. We employ people with experience in international corporations as well as students of the best technical and business universities. Find out more: https://devsdata.com/

🏢 Summary: Senior Frontend Engineer role focused on leading development of a high-traffic web application for shipping management and rate comparison. The position involves end-to-end frontend ownership, from translating designs into production-ready interfaces to optimizing performance and accessibility. You will shape architecture decisions and maintain standards within a React/TypeScript monorepo environment. 🗂️ Requirements: 8+ years of production frontend development experience, 3+ years in senior role within scale-up or start-up environment, Deep expertise in React and TypeScript, Strong knowledge of state management and component architecture, Proficiency in HTML semantics and modern CSS, Experience with web performance optimization and Core Web Vitals, Practical expertise in WCAG 2.2 AA accessibility standards, Experience with unit, integration, and end-to-end testing, Experience working with monorepos, Ability to contribute to frontend and API architecture decisions 📃 Skills: React, TypeScript, JavaScript, HTML, CSS, Grid, Flexbox, WCAG, CoreWebVitals, Testing, Monorepo, API, AWS, Snowflake, Figma 🏢 Description: Senior Frontend Engineer Our Client is an ambitious tech company on a mission to create a frictionless shipping experience for SMEs. They wrap real-time pricing, comparison, booking, and tracking into a clean and unified interface, replacing outdated logistics processes with a seamless digital platform. Role We are looking for an experienced Senior Frontend Engineer to play a central role in shaping a web app where thousands of customers every week sign up, compare rates, manage integrations, and book shipments. You will work end-to-end—from understanding customer problems to shipping production code—while leading frontend work on a core value team (Customer Experience, Marketplace, or SaaS). Responsibilities Plan and lead frontend development within your value team, collaborating closely with PMs, designers, and backend engineers. Translate designs into production user interfaces that are accessible, performant, well-tested, and consistent with the rest of the product. Build prototypes to put working code in front of customers when validating product ideas. Own web performance on the surfaces you touch, ensuring excellent Core Web Vitals to boost conversion rates. Champion accessibility across the platform (WCAG 2.2 AA is the baseline). Contribute to architecture decisions that cross the frontend/backend line, including API boundaries and real-time updates. Maintain shared standards across a React/TypeScript monorepo through code reviews and technical councils. Mentor junior engineers and contribute to the evolution of the company's design system. Key competences 8+ years of experience writing production frontend code, with the last 3+ at a senior level in a scale-up/start-up environment. Deep React and TypeScript experience, with strong opinions on state management and component architecture. Solid web fundamentals: HTML semantics, modern CSS (Grid, Flexbox, container queries), browser rendering pipelines, and the network layer. Accessibility expertise as a practitioner skill, capable of spotting WCAG issues during design reviews. Fluency in web performance, measuring and optimizing Core Web Vitals on real products. High testing maturity (unit, integration, and end-to-end tests). Excellent written and spoken English communication skills. Bonus points for: Experience with large-scale monorepos, background in logistics/marketplaces/B2B SaaS, contributing to design systems, embedding AI-assisted features, or a working knowledge of Go. Salary and Conditions Salary up to 7000 Euro per month 100% remote from Poland B2B contract signed directly with our Client Start ASAP Benefits Work with a modern tech stack (React, TypeScript, AWS, Snowflake, Figma, Claude Code, etc.) A curious, collaborative, low-ego culture within a Great Place to Work certified environment