Build Seamless Checkout Experiences That Drive Conversion — Join Us in Madrid! At FERO, we’re looking for a Senior Frontend Developer to lead the development of a next-generation checkout experience. You’ll design and build performant, user-friendly interfaces in React, collaborate closely with backend teams, and ensure smooth integrations with e-commerce platforms and APIs that power our product. Who We Are We're FERO, a high-growth startup reinventing the checkout and payment experience to help our customers increase conversion and revenue. Backed by top-tier VCs, we’re building our future from the heart of Madrid, combining cutting-edge tech with a collaborative, data-driven culture. We offer competitive pay, employee equity, and the chance to make a real difference in an environment that values curiosity, creativity, and impact. What You'll Do Lead Frontend Development: Architect and implement modern, responsive checkout experiences using React, JavaScript, HTML, and CSS. Collaborate Across Teams: Work closely with backend engineers (PHP/Symfony, Magento, WooCommerce), designers, and product managers to deliver seamless, high-performing user experiences. Integrate Systems: Connect to backend APIs (REST, GraphQL), payment gateways, and shipping modules to ensure smooth and secure checkout flows. Maintain Quality: Write clean, testable, maintainable code, applying best practices for performance, accessibility, and security. Optimise for Conversion: Use data and UX best practices to improve checkout performance and conversion rates. Stay Ahead: Keep up-to-date with the latest trends in React, frontend tooling, and e-commerce technology. What We Offer Innovative Environment: Work on cutting-edge solutions in a greenfield setting. Growth Opportunities: Join us early and grow with us professionally and personally. Collaborative Culture: Be part of a friendly, creative, and supportive team. Flexible Work: Hybrid model - 3 days in office, 2 days WFH. Competitive Compensation: Great pay, employee equity, and private health insurance partially sponsored by FERO. Who You Are Experienced Frontend Developer: 5+ years of professional frontend development experience, with deep expertise in React and modern JavaScript. Backend-Aware: Comfortable working with NodeJS + PHP-based backends and understanding systems like Magento 2 and WooCommerce (not a PHP coder, but you can read and collaborate on backend-related tasks). API Fluent: Skilled at integrating with REST and GraphQL APIs. E-Commerce Enthusiast: Familiar with checkout flows, payment system integrations, and UX best practices for e-commerce. Performance & Accessibility Focused: You know how to build fast and accessible experiences. Collaborative & Proactive: You enjoy working in a team and aren’t afraid to ask questions or speak up with ideas. Growth Mindset: Always eager to learn and adapt to new technologies and challenges. Eligible to Work in Spain Fluent in both written and spoken English Ready to Join Us? Excited to make a difference? Send us your English CV and let's embark on this amazing journey together! ✨