Senior Full-Stack Software Engineer

📍 Location: Barcelona, Spain (Hybrid) 💼 Employment: Full-time 🚀 ABOUT OUR CLIENT Our client is building the AI platform that will redefine the future of hardware engineering. Their product brings together system architecture, requirements, verification, and engineering workflows into one intelligent platform, helping engineering teams design and build the world's most advanced hardware systems faster and more efficiently. From aerospace and defense to robotics, transportation, and semiconductor technologies, they're creating the AI infrastructure that will power the next generation of engineering. This is an early-stage company where every engineer has a direct impact on the product, the technology, and the future of the business. 💡 ABOUT THE ROLE As a Senior Full-Stack Software Engineer, you'll work directly with the founders and technical leadership to build a next-generation AI product from the ground up. This is a highly hands-on engineering role where you'll own features end-to-end—from architecture and implementation to deployment and continuous improvement. You'll collaborate closely with customers, help solve complex engineering challenges, and influence both product and technical decisions. If you're excited by ownership, modern AI technologies, and building products that solve meaningful real-world problems, this is an opportunity to make a significant impact from day one. 🎯 WHAT YOU'LL DO - Own product development from concept to production - Design and build scalable full-stack applications - Develop modern backend services and intuitive frontend experiences - Translate customer needs into elegant technical solutions - Write clean, maintainable, production-ready code - Collaborate directly with founders, engineers, and customers - Review code and contribute to engineering best practices - Improve infrastructure, CI/CD pipelines, cloud deployments, and observability - Build and integrate AI-powered capabilities across the platform - Help shape the engineering culture as the team grows ✅ WHAT WE'RE LOOKING FOR REQUIRED - 3–6+ years of professional software engineering experience - Strong experience building production SaaS applications - Excellent TypeScript skills across the full stack - Experience with React (or another modern frontend framework) - Strong backend development experience and API design - Solid understanding of PostgreSQL or other relational databases - Experience with Docker, CI/CD, and cloud infrastructure (AWS, GCP, or Azure) - Strong debugging, analytical, and problem-solving skills - Product mindset with the ability to take ownership from idea to delivery - Comfortable working in a fast-moving startup environment - Experience using AI development tools and modern LLM workflows - Fluent English - Based in Barcelona or willing to relocate NICE TO HAVE - Startup or founding engineering experience - Experience building AI-powered applications - Knowledge of RAG, vector databases, or multi-agent systems - Enterprise SaaS experience - Interest in aerospace, robotics, semiconductor, automotive, or other advanced engineering industries 🛠️ TECH STACK You'll work with modern technologies including: - TypeScript - React - PostgreSQL - REST / tRPC APIs - Docker - GitHub Actions / CI/CD - AWS, GCP, or Azure - AI development tools and LLM workflows 🌟 WHY JOIN? - Build a category-defining AI platform from an early stage - Work directly with experienced founders and technical leaders - Own meaningful product decisions and features from day one - Solve challenging engineering problems with real-world impact - Competitive salary plus meaningful equity - Join a high-performing team where your work will directly shape the future of the company 📋 ADDITIONAL INFORMATION - Hybrid role based in Barcelona, Spain - Applicants must have the right to work in the EU - Some projects may require eligibility for NATO security clearance due to collaboration with aerospace and defense organizations - Language learning is…