Senior Backend Python 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 or Staff Backend Engineer role focused on architecting and scaling AI-native backend systems for a modern accounting platform. The position involves designing distributed services, building high-performance APIs, and establishing engineering standards to support rapid, reliable product delivery. You will work closely with Product, AI, and Operations teams to develop agentic systems and scalable data pipelines. 🗂️ Requirements: 5–10+ years of backend engineering experience, Proven experience designing, building, and operating production backend systems at scale, Strong expertise in API design, Strong expertise in data modelling, Deep understanding of distributed systems trade-offs, Hands-on experience with AWS or GCP in production, Practical experience with CI/CD in high-frequency deployment environments, Experience implementing testing and deployment strategies, Strong knowledge of observability practices, Experience participating in on-call rotations 📃 Skills: TypeScript, Node.js, React, AWS, GCP, Terraform, PostgreSQL, OpenAI, Azure, CI/CD, APIs, DistributedSystems 🏢 Description: ABOUT THE ROLE We're looking for a Senior or Staff Backend Engineer to own and evolve our backend services as we scale. This is a broad, high-impact role — you'll architect new features, build the systems that underpin our core product, and set the engineering standards that shape how the whole team works. The focus is on building a modern, AI-native developer experience. That means working closely with Product, AI, and Operations teams to design agentic systems, distributed data pipelines, and scalable incident response infrastructure — and doing it in a way that lets the team ship with confidence multiple times a day. WHAT YOU'LL WORK ON Architecture and feature design Partner with Product, AI, and Operations teams to architect new features and complex agentic systems. Make clear architectural trade-offs that balance platform, product, and business goals. Backend services and APIs Build and maintain the backend services and APIs that power the core product. Ensure systems are secure, well-tested, and high performance. Distributed systems Design and implement distributed services to orchestrate data pipelines, automate investigations, and enable incident response at scale. Operational excellence Own operational best practices so the team can ship multiple times a day with confidence. Healthy on-call culture and strong observability are part of what you'll build and maintain. Engineering standards Set the bar for writing, communication, and system design across the team. Your influence will shape how a modern AI-native product is built. WHAT WE LOOK FOR 5–10+ years of backend engineering experience A strong track record designing, building, and operating production backend systems at scale. Deep backend fundamentals Expertise in API design, data modelling, and reasoning about distributed systems trade-offs. You understand the nuances, not just the patterns. AWS or GCP hands-on experience Solid understanding of how infrastructure decisions impact application reliability and performance. You've run things in production, not just designed them. CI/CD in practice Practical experience with testing and deployment strategies in high-frequency shipping environments. Observability and on-call maturity A solid grasp of what good observability looks like and how to build healthy on-call practices that don't burn people out. Bonus Experience at an early-stage or scaling startup. Exposure to modern AI and ML systems. Experience shipping product without a dedicated product manager. TECH STACK TypeScript, React, Node.js, AWS, Terraform, PostgreSQL, OpenAI, Azure AI. The team uses GitHub, Slack, Linear, Figma, and Notion day to day. THE TEAM Small, senior, and in-person. The office is in central Wrocław, next to the main train station. The expectation is 4–5 days a week in the office. Relocation support is available for the right candidate. COMPENSATION & BENEFITS Salary $130,000 – $190,000 USD depending on experience, plus competitive equity. Wellness and commute stipend $100 per month. Hardware Premium hardware provided — MacBook Pro and AirPods. Food Daily in-office lunch and dinner. Time off 20 PTO days plus 9 US public holidays. Relocation Support available for candidates relocating to Wrocław.

🏢 Summary: Senior or Staff Backend Engineer role focused on architecting and scaling AI-native backend services for a modern accounting platform. The position involves designing distributed systems, building secure and high-performance APIs, and establishing engineering standards to support rapid, reliable product delivery. You will work closely with Product, AI, and Operations teams to build scalable data pipelines and incident response infrastructure. 🗂️ Requirements: 5–10+ years of backend engineering experience, Proven experience designing and operating production backend systems at scale, Strong expertise in API design and data modelling, Deep understanding of distributed systems and architectural trade-offs, Hands-on experience with AWS or GCP in production environments, Practical experience with CI/CD pipelines and automated testing, Experience building and maintaining observability and on-call practices 📃 Skills: TypeScript, Node.js, React, AWS, GCP, Terraform, PostgreSQL, OpenAI, Azure, CI/CD, APIs, DistributedSystems, DataModelling, Observability 🏢 Description: ABOUT THE COMPANY We're an applied AI company building an AI-native alternative to legacy accounting software — a market worth tens of billions in annual recurring revenue. Our mission is to help entrepreneurs focus on what matters in their business and life, and to help their accountants become more strategic. We've raised $20M from a group of top-tier investors and have grown ARR 60% month-on-month since our public launch. We now serve thousands of businesses and are expanding our product to serve accountants directly — creating a two-sided platform where both business owners and their accountants use and recommend us. We're at an early but proven stage, moving fast, and building a world-class engineering team in Wrocław to match our ambition. ABOUT THE ROLE We're looking for a Senior or Staff Backend Engineer to own and evolve our backend services as we scale. This is a broad, high-impact role — you'll architect new features, build the systems that underpin our core product, and set the engineering standards that shape how the whole team works. The focus is on building a modern, AI-native developer experience. That means working closely with Product, AI, and Operations teams to design agentic systems, distributed data pipelines, and scalable incident response infrastructure — and doing it in a way that lets the team ship with confidence multiple times a day. WHAT YOU'LL WORK ON Architecture and feature design Partner with Product, AI, and Operations teams to architect new features and complex agentic systems. Make clear architectural trade-offs that balance platform, product, and business goals. Backend services and APIs Build and maintain the backend services and APIs that power the core product. Ensure systems are secure, well-tested, and high performance. Distributed systems Design and implement distributed services to orchestrate data pipelines, automate investigations, and enable incident response at scale. Operational excellence Own operational best practices so the team can ship multiple times a day with confidence. Healthy on-call culture and strong observability are part of what you'll build and maintain. Engineering standards Set the bar for writing, communication, and system design across the team. Your influence will shape how a modern AI-native product is built. WHAT WE LOOK FOR 5–10+ years of backend engineering experience A strong track record designing, building, and operating production backend systems at scale. Deep backend fundamentals Expertise in API design, data modelling, and reasoning about distributed systems trade-offs. You understand the nuances, not just the patterns. AWS or GCP hands-on experience Solid understanding of how infrastructure decisions impact application reliability and performance. You've run things in production, not just designed them. CI/CD in practice Practical experience with testing and deployment strategies in high-frequency shipping environments. Observability and on-call maturity A solid grasp of what good observability looks like and how to build healthy on-call practices that don't burn people out. Bonus Experience at an early-stage or scaling startup. Exposure to modern AI and ML systems. Experience shipping product without a dedicated product manager. TECH STACK TypeScript, React, Node.js, AWS, Terraform, PostgreSQL, OpenAI, Azure AI. The team uses GitHub, Slack, Linear, Figma, and Notion day to day. THE TEAM Small, senior, and in-person. The office is in central Wrocław, next to the main train station. The expectation is 4–5 days a week in the office — this is a deliberate choice, not a compromise. Relocation support is available for the right candidate. COMPENSATION & BENEFITS Salary $130,000 – $190,000 USD depending on experience, plus competitive equity. Wellness and commute stipend $100 per month. Hardware Premium hardware provided — MacBook Pro and AirPods. Food Daily in-office lunch and dinner. Time off 20 PTO days plus 9 US public holidays. Relocation Support available for candidates relocating to Wrocław.

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

🏢 Summary: Senior AI Software Engineer – Backend role focused on designing, building, and scaling production-grade AI backend services, including LLM integrations, RAG pipelines, and distributed cloud-native systems. The position emphasizes reliable, observable, and secure AI solutions deployed in AWS using modern backend and infrastructure practices. You will work in an Agile environment delivering scalable APIs, microservices, and AI-driven workflows for enterprise use cases. 🗂️ Requirements: Bachelor’s degree in Computer Science, Software Engineering, Data Engineering, or related field, 6+ years backend or software engineering experience, Hands-on experience delivering AI-enabled or data-intensive backend solutions, Proficiency in at least one backend language: Python, Java, Go, Kotlin, C#, or TypeScript, Strong experience building REST APIs, microservices, and distributed systems, Experience with Python backend frameworks such as FastAPI and async programming, Experience integrating LLMs or cloud AI services with orchestration layers, Knowledge of RAG, vector search, and semantic retrieval concepts, Experience with SQL and NoSQL databases, Experience with AWS cloud services and cloud-native architectures, Experience with Terraform or infrastructure-as-code tools, Experience with Git and Agile/Scrum methodologies, Knowledge of testing, monitoring, logging, and AI evaluation practices 📃 Skills: Python, Java, Go, Kotlin, C#, TypeScript, FastAPI, REST, Microservices, LLM, RAG, Vector, SQL, NoSQL, AWS, Terraform, Git, Scrum, Kubernetes, Docker, CI/CD, Async, Serverless, Containers 🏢 Description: YOUR CONTRIBUTION Our culture is agile and collaborative, and we genuinely believe our people are some of the best with which you’ll ever work. We are looking for a skilled and passionate Senior AI Software Engineer – Backend to join our Centre of Excellence and the SWE team to design, build and scale production-grade AI services, intelligent workflows, and backend platforms that create measurable business value. YOUR “DAY-TO-DAY”: Design, develop and operate production-grade AI backend services, APIs, and event-driven components with strong focus on scalability, reliability, latency, and cost efficiency. Build and integrate capabilities based on LLMs and other AI services, including prompt orchestration, structured outputs, tool calling, and workflow automation. Develop retrieval and knowledge integration patterns such as RAG, vector search, and metadata-driven content pipelines for enterprise use cases. Participate and support Agile methods and frameworks by taking part in planning events, daily stand-ups, code reviews, and technical discussions. Collaborate closely with product, platform, frontend, DevOps, security, and data stakeholders as a valued member of a self-managing, cross-functional SWE team. Implement robust observability, evaluation and guardrails for AI solutions, including logging, tracing, monitoring, feedback loops and incident troubleshooting. Manage and optimize scalable distributed systems on the Cloud, using secure-by-design and infrastructure-as-code practices. Develop automated tests and evaluation suites to validate backend logic, model behavior, regression scenarios, and non-functional requirements. Translate product and business needs into reliable technical designs, reusable services, and maintainable integration patterns. Continuously improve architecture, developer experience, and engineering standards by contributing to best practices, reviews, and technical mentorship within the Backend community. BACKGROUND AND QUALIFICATIONS: Bachelor's Degree or higher in Computer Science, Software Engineering, Data Engineering, or related field, with appropriate professional experience. Proven work experience as a Backend Engineer or Software Engineer for 6+ years, with hands-on delivery of AI-enabled or data-intensive backend solutions. Strong experience with Agile delivery frameworks such as Scrum and modern source code management practices using Git. Knowledge of AI engineering patterns such as agentic workflows, semantic caching, prompt/version management, and human-in-the-loop controls. Strong proficiency in one or more backend languages such as Python, Java, Go, Kotlin, C#, or TypeScript, with production experience building APIs and services. Solid experience designing and operating backend services, microservices, and distributed systems, including RESTful APIs, asynchronous processing, and messaging patterns. Hands-on experience with Python-based AI/backend frameworks and service development patterns, such as FastAPI, async programming, data validation, and structured outputs. Experience integrating foundation model or cloud AI services and building reliable orchestration layers for prompts, tools, and model interactions. Good knowledge of data access patterns and storage technologies, including SQL and NoSQL databases, caching, and vector databases or semantic retrieval concepts. Experience with AWS cloud services and cloud-native engineering practices, including serverless, containers, observability, and infrastructure automation. Experience with Terraform or other infrastructure-as-code tooling. Knowledge of AI solution quality practices, including testing strategies, evaluation, monitoring, security, privacy, and responsible-use guardrails. Knowledgeable about software architecture, design patterns, logging, monitoring, and performance optimization. Excellent analytical and time management skills, strong teamwork mindset, and a pragmatic problem-solving attitude. Passionate about software engineering, continuous learning, and the practical adoption of emerging AI technologies. ADDITIONAL EXPERIENCE PREFERRED OR HELPFUL: Experience with cloud AI platforms and managed model services, preferably in AWS environments. Experience with Kubernetes, Docker containers, and CI/CD pipelines for deploying and operating AI-enabled services. Experience with product and collaboration tools such as Jira and Confluence. Summary: Senior AI Software Engineer – Backend Role in a nutshell: A senior backend engineer focused on building and scaling production-grade AI services — think LLM integrations, RAG pipelines, agentic workflows, and cloud infrastructure — within a collaborative, cross-functional team. Experience needed: 6+ years in backend/software engineering, with hands-on AI or data-intensive delivery. Must-have tech: Python (FastAPI, async), REST APIs, microservices, Terraform, AWS, SQL/NoSQL/vector databases, Git, Agile/Scrum. Nice to have: Kubernetes, Docker, CI/CD, Terraform, Jira/Confluence. Key soft skills: Strong communicator, team player, pragmatic problem-solver, passionate about AI and continuous learning. Degree: Computer Science, Software Engineering, or related field. The right candidate is someone who bridges solid backend engineering fundamentals with practical AI delivery experience — not just a data scientist or ML researcher, but an engineer who ships reliable, observable AI products in production.

🏢 Summary: Senior Backend Engineer role focused on transforming a mission-critical e-commerce domain supporting subscriptions and purchasing journeys for millions of users. The position centers on migrating a monolithic system to scalable microservices, improving performance and reliability, and shaping the future architecture of a global platform. Engineers will work with event-driven systems and modern AI tools while owning solutions end-to-end. 🗂️ Requirements: 5+ years of professional backend engineering experience, Strong experience designing and operating microservices architectures, Experience modernising legacy systems and decomposing monoliths, Solid understanding of distributed systems and scalable backend design, Commercial experience with Go, Java, Kotlin or Scala, Hands-on experience with Kafka or similar event-streaming technologies, Hands-on experience with PostgreSQL, Hands-on experience with Docker and Kubernetes, Experience with CI/CD pipelines, Practical experience using AI coding assistants (Claude Code, Cursor, Copilot or similar), Ability to review and validate AI-generated code, Comfortable owning solutions from idea to production 📃 Skills: Go, Golang, Java, Kotlin, Scala, Kafka, PostgreSQL, Docker, Kubernetes, CI/CD, GraphQL, DDD, TDD, BDD, Microservices 🏢 Description: As a Senior Backend Engineer, you will join a global e-commerce technology organisation serving millions of customers across multiple international markets. The team is responsible for a critical customer-facing domain supporting subscriptions, plans, and purchasing journeys used daily by millions of users. This role focuses on transforming a mission-critical domain by modernising legacy systems, reducing technical debt, and building the next generation of scalable services. What You'll Do Build & Scale Core Services - Design, develop, and maintain scalable backend services within a distributed microservices architecture. - Build reliable systems supporting millions of customer interactions. - Improve performance, reliability, and scalability across critical customer-facing services. Drive Modernisation - Lead the migration of key business domains from monolithic systems to modern microservices. - Reduce technical debt and improve long-term maintainability. - Design solutions that support future platform growth. Shape Architecture - Participate in architecture discussions and technical decision-making. - Design orchestration layers supporting complex customer journeys and business processes. - Help define engineering standards and best practices. Work with Event-Driven Systems - Build and operate services powered by event-driven architectures. - Work extensively with Kafka and real-time lifecycle events. - Design resilient and observable distributed systems. Raise Engineering Standards - Conduct code reviews and provide technical guidance. - Promote best practices across software development, testing, deployment, and observability. - Contribute to a culture of ownership and continuous improvement. AI-Powered Engineering - Use modern AI tools and coding agents throughout the software development lifecycle. - Leverage AI for onboarding, architecture exploration, implementation, testing, debugging, and productivity improvements. - Apply engineering judgement to validate and safely integrate AI-generated outputs. What We're Looking For Backend Engineering Expertise - 5+ years of professional backend engineering experience. - Strong experience designing and operating microservices architectures. - Experience modernising legacy systems and decomposing monoliths. - Solid understanding of distributed systems and scalable backend design. Technical Stack - Commercial experience with Go (Golang), Java, Kotlin or Scala. - Engineers from a JVM background should be open to working in a Go-driven environment. - Hands-on experience with Kafka or similar event-streaming technologies. - Hands-on experience with PostgreSQL. - Experience with Docker, Kubernetes, and CI/CD pipelines. Product & Ownership Mindset - Comfortable owning solutions from idea through production. - Strong problem-solving skills and ability to make technical trade-offs. - Experience collaborating with product, business, and engineering stakeholders. AI Fluency - Practical experience using AI coding assistants such as Claude Code, Cursor, Copilot, or similar tools. - Understanding of how context, prompts, constraints, and validation influence AI-generated outputs. - Ability to critically review and verify AI-generated solutions. Nice to Have - Experience with subscription-based products. - Experience in e-commerce environments. - GraphQL knowledge. - Familiarity with DDD, TDD, and BDD practices. What We Offer - Opportunity to build systems used by millions of customers globally. - High-impact engineering work with significant architectural ownership. - International collaboration across distributed engineering teams. - End-to-end ownership from idea to production. - Hybrid working model (3 days per week in the Warsaw office). - B2B cooperation model. - 30 days of paid annual leave. - Modern office located in Warsaw city centre. - Continuous learning and professional growth opportunities.

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

🏢 Summary: Senior Fullstack Engineer role focused on delivering full-stack solutions within an AI-integrated SDLC where AI is embedded across planning, development, review, testing, and deployment. The position combines backend and frontend engineering with AI orchestration, automation, and cloud-native architecture in a remote-first setup. The engineer will also evolve shared AI toolchains and contribute to architectural and code quality standards. 🗂️ Requirements: Team-level AI-integrated SDLC experience across planning, development, review, testing, deployment, Shared AI toolchain management under version control, Hands-on use of Claude Code, GitHub Copilot, Cursor or equivalent as team tools, Building and maintaining custom AI skills and sub-agents for team use, Experience with parallel AI agent orchestration, Spec-driven development using OpenAPI, ADRs, PRDs as AI context, AI-assisted code review integrated into PR process, Working knowledge of AI orchestration frameworks, Backend development with .NET / C# and ASP.NET Core, Frontend development with TypeScript and React or Angular, Experience with SQL databases and ORM frameworks, Experience with Docker and Kubernetes, Experience with CI/CD pipelines, Experience with cloud platforms (Azure, AWS, or GCP) 📃 Skills: C#, .NET, ASP.NET, SQL, SQLServer, PostgreSQL, EFCore, OAuth, JWT, Python, Java, Node.js, TypeScript, JavaScript, React, Angular, LangChain, LlamaIndex, CrewAI, Docker, Kubernetes, GitHubActions, AzureDevOps, Azure, AWS, GCP, OpenAPI, CQRS, DDD, EventSourcing, Microservices 🏢 Description: We are looking for a Senior Fullstack Engineer who combines deep technical expertise with real, team-level experience working in an AI-integrated software development lifecycle. Individual use of AI coding assistants is not sufficient for this role. We are specifically looking for engineers who have worked in teams where AI was embedded into every phase of delivery — from planning and design through development, review, testing, and deployment. We follow a remote-first setup with no mandatory regular office visits for this position. From time to time, you may be invited to join in-person meetings in one of our offices (Warsaw, Lodz, Wroclaw, Gdansk, or Bialystok), for example for client visits or team reunions. AI-First Requirements Experience working in an AI-enabled engineering team is mandatory — not a personal workflow preference. You have been part of a team where AI was systematically embedded across all delivery phases: planning, development, review, testing, and deployment. You can speak from direct experience about how it worked, what failed, and what you would change. Specific mandatory requirements: Team-level AI-integrated SDLC experience — shared toolchain, shared configurations, shared assets under version control Hands-on with Claude Code, GitHub Copilot, Cursor, or equivalent as a team tool, not only personal usage Built and maintained custom skills and sub-agents used across a team, not just personally Experience with parallel agent orchestration for concurrent workstream execution Disciplined plan → review plan → execute approach with AI involved at every phase Maintained shared prompt libraries, skill repositories, or agent configurations in version control AI-assisted code review integrated into the PR process: CodeRabbit, Copilot review, or similar Experience with spec-driven or document-driven development where structured specifications (OpenAPI, ADRs, PRDs) serve as AI context inputs, not just human references Working knowledge of at least one AI orchestration framework: LangChain, LlamaIndex, Microsoft Agent Framework, CrewAI, or equivalent Automation-first mindset: proactively identify repetitive or inefficient parts of current work and automate them using AI and other available tools. Cost-aware AI usage: understanding how AI credits are consumed across different tools, models, and workflows, and ability to choose the most appropriate model or approach for each task. Technical Requirements Backend: .NET / C#, ASP.NET Core, SQL Server / PostgreSQL, EF Core, OAuth 2.0 / JWT. Python, Java, or Node.js is a strong plus. Frontend: TypeScript, JavaScript, React(preferable) and/or Angular, state management, async patterns, frontend testing. Architecture: Full spectrum from monolith to microservices — DDD, CQRS, Event Sourcing, event-driven design, message brokers. Infrastructure: Docker, Kubernetes, CI/CD (GitHub Actions / Azure DevOps), Azure / AWS / GCP, structured observability. Responsibilities Deliver full-stack features to a high standard of quality, performance, and reliability Contribute to architectural decisions and system design trade-offs Evolve and maintain the team's shared AI toolchain across all SDLC phases Conduct code reviews including AI-assisted tooling; uphold and enforce engineering best practices Proactively surface risks, bottlenecks, and security concerns Communicate and collaborate directly with clients in English Mentor engineers on both technical fundamentals and AI-augmented workflow practices Professional Qualities Ownership mindset · Strong written and verbal English · Comfortable in client-facing roles · Raises the AI workflow maturity of those around them

🏢 Summary: Lead AI Software Developer role focused on architecting and scaling AI-powered applications, backend systems, and multi-agent workflows across cloud and enterprise environments. The position involves designing secure integrations, optimizing LLM-based solutions, and leading technical delivery and best practices. It combines hands-on AI development with backend architecture and technical leadership. 🗂️ Requirements: Degree in Computer Science, AI, Data Science or related field, 8+ years of software engineering experience, 5+ years of Python backend development in production, Experience building and scaling Python applications, Hands-on experience with AI Agents, RAG and MCP, Experience with AWS or Azure cloud platforms, Experience with storage systems and databases, Knowledge of containerization and Kubernetes, Experience with API integrations and enterprise system connectivity, Leadership and mentoring experience 📃 Skills: Python, AWS, Azure, Kubernetes, RAG, MCP, APIs, Cloud, Databases, Containerization, AI, LLM 🏢 Description: We are seeking an experienced Lead AI Software Developer to design and scale AI-powered applications and integrations. In this role, you will architect backend systems, lead AI agent development, and ensure secure, scalable integration across cloud platforms and enterprise systems. Key Responsibilities Design and maintain middleware, APIs, and connectors integrating AI agents with enterprise systems Architect scalable backend services and cloud-based solutions (AWS/Azure) Develop and optimize multi-agent workflows and adaptive decision logic Fine-tune prompts and LLM-based solutions for domain-specific use cases Lead code reviews, mentor developers, and define development best practices Drive complex API integrations with internal and external AI platforms (incl. MCP servers) Remove technical roadblocks and ensure timely delivery Collaborate with AI, Data, and Platform teams to optimize automation architectures Maintain technical documentation and promote continuous improvement Requirements Degree in Computer Science, AI, Data Science, or similar field 8+ years of software engineering experience, including 5+ years of Python backend development (production) Strong experience building and scaling Python applications Hands-on experience with AI technologies (AI Agents, RAG, MCP) Experience with cloud platforms (AWS or Azure), storage, databases, and AI services Knowledge of containerization and Kubernetes Experience with API integrations and enterprise system connectivity Strong leadership and mentoring experience Excellent communication skills; fluent in Polish and English (min. B2); German is a plus Willingness to travel internationally (~10%) Nice to have: Experience with LangChain, LangGraph, multi-agent systems, prompt engineering, and LLM fine-tuning. What We Offer Work in a global and innovative technology environment Direct impact on enterprise AI and automation solutions Professional development and access to training programs Hybrid work model with flexible hours (central Wroclaw office) Competitive benefits package, cafeteria system, CSR initiatives, and employee clubs