Senior Full Stack Software Engineer (Python, React), Remote, Madrid/BarcelonaHelp build high-performance web applications used by thousands of users.We're looking for aSenior Full Stack Software Engineerwith a strongbackend focus in Pythonand solidReact experienceto help design and scale modern web applications.This role is adecuado for someone who enjoys solving complex engineering challenges, making architectural decisions, and building systems designed for reliability and performance at scale.You'll work closely with engineers and stakeholders to deliver robust, user-friendly applications while contributing to both backend architecture and modern frontend improvements.About the RoleAs aSenior Full Stack Engineer, you will play a key role in shaping the technical direction of the platform.You'll lead backend architecture decisions, build scalable services, and help evolve the frontend experience using modern technologies.The platform supportsthousands of concurrent users and high-frequency external integrations, so performance, stability, and scalability are critical.You'll also help drive engineering best practices, improve testing coverage, and contribute to continuous technical improvements across the stack.What You'll Be DoingLeading thedesign and development of backend servicesusing PythonBuilding scalable APIs and services capable of supportinghigh traffic and concurrent usersContributing tomodern frontend developmentusing React and TypeScriptMakingkey architectural and technical decisionsImprovingsystem performance, reliability, and scalabilityWritingwell-tested backend and frontend codeImplementingend-to-end and integration testing using PlaywrightCollaborating with engineers and stakeholders to deliver high-quality solutionsSupporting ongoingtechnology improvements and engineering best practicesWhat We're Looking ForSolid professional background developingbackend services with PythonSeveral years of experience working withJavaScript for web applications, ide