Frontend Software Engineer - React (m/f/d)

Job DescriptionSixt is building toward a spec-and-review way of working: engineers turn product problems into clear specifications, direct AI coding agents to build them, and own the quality of what ships. This role sits at that level — you deliver primarily by specifying and reviewing, backed by the frontend depth to read, debug, and stand behind every change. YOUR ROLE AT SIXT Turn ambiguous product problems into clear, testable specifications — success criteria and edge cases spelled out — that agents can execute againstWork with AI tools, adapt and improve agentic ecosystem by building strong guardrails and processes that keeps the product stableDrive agents in small, verifiable steps, correcting and re-steering when the output drifts from intentOwn what your agents ship to production: debug to root cause, and encode prevention — a test, a lint rule, an agent constraint — so the same issue is caught automatically next time.Ship medium-to-complex features end-to-end with minimal guidanceDeliver production-quality, reusable React components and integrate reliably with backend YOUR SKILLS MATTER Bachelor's/Master's in Computer Science or a related field, with 3–6 years of frontend software engineering experience.Strong React.js — component contracts, state management, rendering/performance behavior — with a solid grasp of how the browser parses, renders, and paints a page, enough to guide AI toward semantic, accessible HTML. Depth is important: it lets you review and trust agent output.Proficient with HTML, CSS, JSON, build tools, and Git, with excellent debugging skills. Treats cross-browser compatibility and measurable frontend performance as defaults, not afterthoughts.Sets up agentic workflows: delegates well-scoped tasks to AI agents, reviews output critically for correctness, standards, and architectural drift, recognises low-value output and course-corrects before it merges — and can explain any of it.Shares agent workflows to speed up the team and onboard them on good AI practices, discuss trade-offs in reliability, performance, and correctness with the teamGood problem-solving and communication with strong ownership across execution and delivery: collaborates with Product/peers, challenges unclear framing, builds judgment on architecture and outcomes WHAT WE OFFER A Global Tech Hub in Lisbon Join a thriving international tech community and work alongside engineers, product experts, and business teams who turn ideas into real impact. Our hubs at Factory Lisboa in Beato and ARTs Lisboa in Parque das Nações are where great tech gets built Learning & Knowledge Exchange Level up through regular events with internal and external speakers. We value curiosity, continuous learning, and open exchange – across teams, disciplines, and borders Flexible Work Setup Two office days a week, flexible hours, and modern spaces built for both deep focus and team collaboration – work the way that brings out your best Time Off & Wellbeing Enjoy 28 vacation days per year, an additional day off on your birthday, one volunteer day annually, and private health insurance that also covers your spouse and children free of charge Practical Everyday Benefits Get a yearly Coverflex allowance and a daily meal allowance to make everyday life a little easier SIXT Perks Get exclusive rates on all SIXT services, with special discounts extended to your family and friends. Because great perks are even better when you can share them