Senior Full-Stack Engineer (Node.js/React) – Sustainable Tech Unicorn (O Chazo)

About the client A German Sustainable Tech Unicorn that is redefining how global corporations handle transparency. Backed by a €130M Series C investment, our client has built a proprietary, serverless cloud infrastructure to ensure human rights and ecological responsibility across global supply chains. Currently in a massive consolidation phase, their Madrid Hub is expanding from 20 to over 100 top-tier engineers in 2026. This is your chance to join a high-growth environment where engineering quality and product ownership are the top priorities. The Mission: Impact at Scale As a Senior Full-Stack Engineer you will be an architect of transparency. You will own the end-to-end development of products that help over 2,000 global companies comply with critical ESG regulations (LkSG, CSDDD). Key Responsibilities System Architecture: Design and optimize scalable full-stack features, focusing on robust backend systems and high-performance frontend interfaces. Infrastructure Innovation: Work directly on a custom-built, serverless cloud ecosystem (the Hub). Technical Leadership: Influence the design of core libraries and microservices architecture used worldwide. Collaborative Strategy: Work in high-density agile squads (4-6 people) alongside tech leads to define the product roadmap. Quality Advocacy: Drive technical excellence through rigorous code reviews, automated testing, and CI/CD best practices. Your Profile Experience: 6+ years of professional experience in Full-Stack development, specifically within product-based companies (no agencies or consultancies). Backend Mastery: Expert-level command of Node.js and TypeScript. Frontend Proficiency: Strong experience with React.js. Architecture Mindset: Deep understanding of microservices, end-to-end product ownership, and scalable design patterns. Communication: Fluent English (C1). Spanish