Senior Fullstack Engineer

Senior Fullstack Engineer (AI-First, On-site Warsaw)Location: Warsaw, Poland On-site work: 5 days per week (office-based role) 📍About the role: We are looking for a highly experienced Fullstack Engineer who builds real production systems and actively works with AI as a core part of their daily development workflow. This is not a remote role and not a junior or mid-level position. You will work on complex, API-driven systems where architecture, correctness, scalability, and long-term maintainability matter. Using AI for coding, design, refactoring, and problem-solving (vibe coding) is a hard requirement, not a nice-to-have. 📝What you will do: • Design, develop, and evolve backend and frontend systems used in production • Build, extend, and maintain robust APIs (both consuming external APIs and developing internal/public ones) • Work daily with AI-assisted development tools as an integral part of your workflow • Make architectural decisions with a focus on scalability, performance, and reliability • Write clean, maintainable, well-structured code with long-term ownership in mind • Collaborate closely with other engineers and product stakeholders in an on-site team • Review, validate, and improve AI-generated code to ensure correctness, security, and performance 📝Must-have requirements: • Strong, proven experience in software engineering (senior-level or higher) • Excellent knowledge of: ○ JavaScript and TypeScript ○ Node.js and modern runtimes such as Bun • Solid hands-on experience with both React and Vue • Deep, practical experience working with APIs:○ designing APIs ○ extending existing APIs ○ integrating third-party APIs • Strong understanding of software architecture and system design • High standards for code quality, readability, and maintainability • Excellent command of AI-assisted development: ○ daily use of tools such as Cursor, Copilot, ChatGPT, or similar ○ ability to critically assess AI output instead of blindly accepting it ○ using AI for refactoring, debugging, testing, documentation, and exploration • Comfortable working in an English-speaking environment 💎Nice to have • Experience with DevOps, infrastructure, or production operations • Experience working on high-traffic or business-critical systems • Background in designing systems that evolve over time rather than one-off projects 📝Important notes • his is a full-time, on-site position in Warsaw • AI-first development is a condition of employment • We are looking for engineers who think in systems, not just frameworks • We offer work on a modern application, A close-knit, experienced, and supportive team, private medical care and sports card If you prefer remote-only work or do not actively use AI in your daily coding, this role is not a good fit.