April 8, 2026
Senior Fullstack (React+Next.js)
Senior • Remote
5,500 - 6,000 USD
Krakow, Poland
#4729
Our Client is building a SaaS platform used globally to streamline business-critical workflows and transform document-driven processes into intelligent, automated systems. Their platform powers agreement lifecycle experiences at a massive scale, serving millions of organizations across highly regulated and enterprise environments.
The team develops a unified, widget-based frontend platform that standardizes how product teams deliver modern, high-performance user interfaces. This platform provides a shared shell, micro-frontend architecture, and automated CI/CD pipelines that distribute versioned UI components globally with high reliability.
Part of the work includes supporting secure, compliance-heavy environments designed for federal-grade workloads. Engineers design systems that are secure by default, privacy-aware, and built on zero-trust principles. The role involves solving advanced platform challenges such as resilient rollouts, deterministic builds, telemetry without exposing sensitive data, and high-availability architecture in constrained environments.
This is an opportunity to shape platform standards, performance practices, and developer tooling in a system operating at meaningful scale.
Responsibilities
Design and implement reusable frontend components within a micro-frontend architecture.
Build and maintain a shared UI platform that enables consistent user experiences across products.
Develop scalable CI/CD pipelines that publish versioned frontend artifacts for global delivery.
Contribute to secure-by-default engineering patterns aligned with compliance requirements.
Optimize performance, observability, and reliability across distributed frontend systems.
Collaborate with cross-functional teams to define platform standards and engineering best practices.
Integrate frontend systems with RESTful and/or gRPC backend services.
Support high-availability deployments in regulated or restricted environments.
Required Qualifications
4+ years of professional software development experience.
Strong proficiency in TypeScript and React.
Experience building reusable, production-grade frontend component libraries.
Experience with frontend testing frameworks and test automation.
Solid experience with Next.js, Node.js, and Express.
Proven track record delivering SaaS products.
Preferred Qualifications
Experience across the full software development lifecycle.
Familiarity with schema modeling (e.g., JSON Schema or XML Schema).
Experience with Agile and test-driven development methodologies.
Experience with Azure DevOps or comparable CI/CD tooling.
Knowledge of micro-frontend frameworks.
Experience building or consuming RESTful or gRPC services.
Strong written communication skills in asynchronous environments.
Passion for platform engineering and high-quality software craftsmanship.
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5,000 - 8,500 USD
🏢 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.
Technology
N-iX
Senior Full-Stack Python Engineer
Senior
Remote
Krakow, Poland
6,000 - 7,100 USD
🏢 Summary: Senior Full-Stack Engineer role focused on building and scaling an AI-powered document processing and automation platform in a cloud environment. The position involves developing backend services in Python and front-end applications in TypeScript while delivering scalable APIs, microservices, and data workflows. The role requires hands-on contribution to architecture, cloud deployment, and integration of AI-driven features. 🗂️ Requirements: 6+ years of professional software engineering experience, Strong proficiency in Python, Experience with FastAPI, Flask, or Django, Solid experience with TypeScript, Experience with React or Next.js, Hands-on experience designing and implementing microservices, Experience building and integrating REST APIs, Strong knowledge of relational or NoSQL databases, Experience with AWS or Azure, Familiarity with CI/CD pipelines, Experience with Docker, Proficiency with Git, Understanding of scalability, reliability, performance, and security principles 📃 Skills: Python, FastAPI, Flask, Django, TypeScript, React, Next.js, REST, Microservices, PostgreSQL, MySQL, MongoDB, Firestore, AWS, Azure, Docker, Git, CI/CD 🏢 Description: Client Overview Our client is a global UK-based financial services and investment banking organization developing an AI-powered document processing and automation platform used across multiple business units. The platform focuses on large-scale data processing, workflow automation, integration with internal systems, and delivering modern digital capabilities for the wider banking group. Position Overview We are looking for a Senior Full-Stack Engineer to join a cross-functional engineering team building core components of the AI-driven document processing platform. This position requires strong backend engineering experience with Python as well as solid front-end or full-stack proficiency with TypeScript (preferably React, Next.js, or similar frameworks). You will work on delivering scalable APIs, microservices, data workflows, and UI components that power document automation features, internal tools, and operational dashboards. The role involves close collaboration with product, architecture, GenAI, and platform engineering teams. This role is ideal for someone who is hands-on, highly technical, and comfortable designing, developing, and deploying production-grade systems in cloud environments (preferably Google Cloud). Key Responsibilities Design, develop, and maintain backend services using Python (FastAPI, Flask, Django, or similar frameworks). Build front-end components and UIs using TypeScript (React, Next.js, or similar frameworks). Develop and integrate REST APIs and microservices, ensuring strong performance, reliability, and observability. Collaborate closely with GenAI engineers to integrate AI-driven features and document-processing flows. Implement data processing pipelines for structured and unstructured data. Contribute to the platform’s architecture, design patterns, and technical decision-making. Write automated tests and ensure a high level of code quality, maintainability, and security. Partner with product managers, designers, and QA engineers to deliver high-quality solutions on time. Document code, service interfaces, workflows, and architectural decisions. Requirements 6+ years of professional software engineering experience, with significant work in both backend and full-stack roles. Strong proficiency in Python (FastAPI, Flask, Django, or similar). Solid experience with TypeScript and modern front-end frameworks (React, Next.js, or similar). Hands-on experience designing and implementing microservices, APIs, and backend systems. Strong understanding of databases: relational (PostgreSQL, MySQL) and/or NoSQL (MongoDB, Firestore). Experience with any cloud providers (AWS/Azure). Familiarity with CI/CD pipelines, Docker, Git, and modern DevOps practices. Strong understanding of software engineering principles: scalability, reliability, performance, and security. Experience working in agile, cross-functional teams on complex products. Excellent communication skills and ability to work with both technical and non-technical stakeholders. Nice to Have Experience working with AI/ML or GenAI-driven systems. Experience with Google Cloud Platform Familiarity with Vertex AI, Gemini, or integration with LLM-powered services. Experience with WebSockets, event-driven architectures, or Pub/Sub. Knowledge of authentication/authorization standards (OAuth2, JWT, IAM). Experience with document processing, OCR, or workflow automation.
Technology
N-iX
Senior .NET Engineer
Senior
Remote
Krakow, Poland
5,500 - 6,000 USD
🏢 Summary: Backend Engineer role focused on building and maintaining scalable, secure platform services for account provisioning and usage. The position involves designing and implementing RESTful and gRPC APIs, microservices, and external integrations in a cloud environment. You will work in an Agile team delivering high-quality enterprise solutions with CI/CD practices. 🗂️ Requirements: Bachelor’s degree in Computer Science, Computer Engineering or related field, or equivalent industry experience, 3+ years of experience developing and maintaining backend services, Experience implementing RESTful or gRPC APIs, Professional server-side development experience, Experience with microservice architecture and design, Experience working with cloud platforms (Azure, AWS, GCP or similar), Experience implementing logging, monitoring, alerts and dashboards, Ability to design scalable, secure and high-availability systems 📃 Skills: C#, REST, gRPC, Microservices, Azure, AWS, GCP, CI/CD, APIs, Logging, Monitoring, Dashboards, Agile 🏢 Description: #4736 14:00-20:00 CET working hours In this role, you will be a member of the Account Provisioning and Usage platform development team. We are responsible for ensuring that customers receive the features and services that they’ve purchased across a growing suite of customer's products and features. You will work closely with product and other engineers to deliver and develop backend platform service features in a scalable and secure manner. You will use your experience working with production web applications at scale to design, implement and maintain RESTful and GRPC APIs, microservices and integrations with external services. A successful person in this role will want to work in an environment where you are challenged to continue learning and growing. Where your voice and opinions will be heard and you can make a real difference. You will work closely with Product Management, Core Engineering, and internal Business and Partner teams to enable delivering value to customers faster. The client is transforming the way that our customers create, commit, and manage agreements. Our team is working on highly visible and impactful work to simplify and modernize the way features are packed and managed across single and multi-account customers and we need talented developers to help us get there! Responsibilities: Designing, developing and maintaining modern web features and service integrations for our backend platform services Delivering secure, performant, scalable and reusable enterprise quality code utilizing Agile practices and a Continuous Integration and Deployment CI/CD pipeline Collaborating through code reviews, pair programming and online remote communication to help ensure we ship scalable, secure and highly available code Mentoring team members who are learning skills which you have mastered Keeping current with the latest software engineering best practices and sharing with the team to continuously increase quality, efficiency and productivity Apply strong analytical skills and ability to investigate and update code that you are unfamiliar with Basic Qualifications: A bachelor’s degree in Computer Science, Computer Engineering, or other related engineering field, or comparable industry experience within a software organization 3+ years of experience implementing and maintaining backend services, including RESTful or grpc API endpoints using a modern software language and/or framework Professional experience with server-side development Experience with microservice architecture, design, and implementation on Azure, AWS, GCP or other cloud environments. Experience writing logging, monitoring, alerts and dashboards to detect and diagnose live issues. Preferred Qualifications: Experience developing in C# Experience working in an agile development environment Experience in integrating with web-based products Strong organizational, problem-solving and communication skills A demonstrated willingness to assist other team members through brainstorming, mentorship, pair-programming, knowledge-sharing and creative problem solving